diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8428f033b7..3af6f8886d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,12 +2,24 @@
 
 ## Unreleased
 
+### Behavioral Changes
+
+- Collections returned by scope (e.g. `getBreadcrumbs`, `getTags`, `getAttachments`) are shared state and should not be mutated. ([#5541](https://github.com/getsentry/sentry-java/pull/5541))
+  - Previously, when going through `CombinedScopeView`, we were returning a copy where mutations didn't show up in the underlying scopes.
+  - This has now changed in order to reduce SDK overhead.
+
 ### Features
 
 - Add experimental `SentrySQLiteDriver` to `sentry-android-sqlite` for instrumenting `androidx.sqlite.SQLiteDriver` ([#5563](https://github.com/getsentry/sentry-java/pull/5563))
   - To use it, pass `SQLiteDriver` to `SentrySQLiteDriver.create(...)`
   - Requires `androidx.sqlite:sqlite` (2.5.0+) on runtime classpath (typically provided by Room or SQLDelight)
 
+### Internal
+
+- Reduce writer buffer size from 8192 to 512 ([#5544](https://github.com/getsentry/sentry-java/pull/5544))
+- Remove redundant event map copies ([#5536](https://github.com/getsentry/sentry-java/pull/5536))
+- Optimize combined scope by adding an early return if only one scope has data ([#5541](https://github.com/getsentry/sentry-java/pull/5541))
+
 ## 8.44.0
 
 ### Features
diff --git a/sentry/src/main/java/io/sentry/CombinedScopeView.java b/sentry/src/main/java/io/sentry/CombinedScopeView.java
index f21f8697fa..ea2d752d44 100644
--- a/sentry/src/main/java/io/sentry/CombinedScopeView.java
+++ b/sentry/src/main/java/io/sentry/CombinedScopeView.java
@@ -171,10 +171,31 @@ public void setFingerprint(@NotNull List<String> fingerprint) {
 
   @Override
   public @NotNull Queue<Breadcrumb> getBreadcrumbs() {
+    final @NotNull Queue<Breadcrumb> globalBreadcrumbs = globalScope.getBreadcrumbs();
+    final @NotNull Queue<Breadcrumb> isolationBreadcrumbs = isolationScope.getBreadcrumbs();
+    final @NotNull Queue<Breadcrumb> currentBreadcrumbs = scope.getBreadcrumbs();
+
+    final boolean hasGlobalBreadcrumbs = !globalBreadcrumbs.isEmpty();
+    final boolean hasIsolationBreadcrumbs = !isolationBreadcrumbs.isEmpty();
+    final boolean hasCurrentBreadcrumbs = !currentBreadcrumbs.isEmpty();
+
+    if (!hasGlobalBreadcrumbs && !hasIsolationBreadcrumbs && !hasCurrentBreadcrumbs) {
+      return getDefaultScopeValue(globalBreadcrumbs, isolationBreadcrumbs, currentBreadcrumbs);
+    }
+    if (!hasIsolationBreadcrumbs && !hasCurrentBreadcrumbs) {
+      return globalBreadcrumbs;
+    }
+    if (!hasGlobalBreadcrumbs && !hasCurrentBreadcrumbs) {
+      return isolationBreadcrumbs;
+    }
+    if (!hasGlobalBreadcrumbs && !hasIsolationBreadcrumbs) {
+      return currentBreadcrumbs;
+    }
+
     final @NotNull List<Breadcrumb> allBreadcrumbs = new ArrayList<>();
-    allBreadcrumbs.addAll(globalScope.getBreadcrumbs());
-    allBreadcrumbs.addAll(isolationScope.getBreadcrumbs());
-    allBreadcrumbs.addAll(scope.getBreadcrumbs());
+    allBreadcrumbs.addAll(globalBreadcrumbs);
+    allBreadcrumbs.addAll(isolationBreadcrumbs);
+    allBreadcrumbs.addAll(currentBreadcrumbs);
     Collections.sort(allBreadcrumbs);
 
     final @NotNull Queue<Breadcrumb> breadcrumbs =
@@ -224,10 +245,31 @@ public void clear() {
 
   @Override
   public @NotNull Map<String, String> getTags() {
+    final @NotNull Map<String, String> globalTags = globalScope.getTags();
+    final @NotNull Map<String, String> isolationTags = isolationScope.getTags();
+    final @NotNull Map<String, String> currentTags = scope.getTags();
+
+    final boolean hasGlobalTags = !globalTags.isEmpty();
+    final boolean hasIsolationTags = !isolationTags.isEmpty();
+    final boolean hasCurrentTags = !currentTags.isEmpty();
+
+    if (!hasGlobalTags && !hasIsolationTags && !hasCurrentTags) {
+      return getDefaultScopeValue(globalTags, isolationTags, currentTags);
+    }
+    if (!hasIsolationTags && !hasCurrentTags) {
+      return globalTags;
+    }
+    if (!hasGlobalTags && !hasCurrentTags) {
+      return isolationTags;
+    }
+    if (!hasGlobalTags && !hasIsolationTags) {
+      return currentTags;
+    }
+
     final @NotNull Map<String, String> allTags = new ConcurrentHashMap<>();
-    allTags.putAll(globalScope.getTags());
-    allTags.putAll(isolationScope.getTags());
-    allTags.putAll(scope.getTags());
+    allTags.putAll(globalTags);
+    allTags.putAll(isolationTags);
+    allTags.putAll(currentTags);
     return allTags;
   }
 
@@ -243,10 +285,32 @@ public void removeTag(@Nullable String key) {
 
   @Override
   public @NotNull Map<String, SentryAttribute> getAttributes() {
+    final @NotNull Map<String, SentryAttribute> globalAttributes = globalScope.getAttributes();
+    final @NotNull Map<String, SentryAttribute> isolationAttributes =
+        isolationScope.getAttributes();
+    final @NotNull Map<String, SentryAttribute> currentAttributes = scope.getAttributes();
+
+    final boolean hasGlobalAttributes = !globalAttributes.isEmpty();
+    final boolean hasIsolationAttributes = !isolationAttributes.isEmpty();
+    final boolean hasCurrentAttributes = !currentAttributes.isEmpty();
+
+    if (!hasGlobalAttributes && !hasIsolationAttributes && !hasCurrentAttributes) {
+      return getDefaultScopeValue(globalAttributes, isolationAttributes, currentAttributes);
+    }
+    if (!hasIsolationAttributes && !hasCurrentAttributes) {
+      return globalAttributes;
+    }
+    if (!hasGlobalAttributes && !hasCurrentAttributes) {
+      return isolationAttributes;
+    }
+    if (!hasGlobalAttributes && !hasIsolationAttributes) {
+      return currentAttributes;
+    }
+
     final @NotNull Map<String, SentryAttribute> allAttributes = new ConcurrentHashMap<>();
-    allAttributes.putAll(globalScope.getAttributes());
-    allAttributes.putAll(isolationScope.getAttributes());
-    allAttributes.putAll(scope.getAttributes());
+    allAttributes.putAll(globalAttributes);
+    allAttributes.putAll(isolationAttributes);
+    allAttributes.putAll(currentAttributes);
     return allAttributes;
   }
 
@@ -272,11 +336,32 @@ public void removeAttribute(@Nullable String key) {
 
   @Override
   public @NotNull Map<String, Object> getExtras() {
-    final @NotNull Map<String, Object> allTags = new ConcurrentHashMap<>();
-    allTags.putAll(globalScope.getExtras());
-    allTags.putAll(isolationScope.getExtras());
-    allTags.putAll(scope.getExtras());
-    return allTags;
+    final @NotNull Map<String, Object> globalExtras = globalScope.getExtras();
+    final @NotNull Map<String, Object> isolationExtras = isolationScope.getExtras();
+    final @NotNull Map<String, Object> currentExtras = scope.getExtras();
+
+    final boolean hasGlobalExtras = !globalExtras.isEmpty();
+    final boolean hasIsolationExtras = !isolationExtras.isEmpty();
+    final boolean hasCurrentExtras = !currentExtras.isEmpty();
+
+    if (!hasGlobalExtras && !hasIsolationExtras && !hasCurrentExtras) {
+      return getDefaultScopeValue(globalExtras, isolationExtras, currentExtras);
+    }
+    if (!hasIsolationExtras && !hasCurrentExtras) {
+      return globalExtras;
+    }
+    if (!hasGlobalExtras && !hasCurrentExtras) {
+      return isolationExtras;
+    }
+    if (!hasGlobalExtras && !hasIsolationExtras) {
+      return currentExtras;
+    }
+
+    final @NotNull Map<String, Object> allExtras = new ConcurrentHashMap<>();
+    allExtras.putAll(globalExtras);
+    allExtras.putAll(isolationExtras);
+    allExtras.putAll(currentExtras);
+    return allExtras;
   }
 
   @Override
@@ -342,6 +427,23 @@ public void removeContexts(@Nullable String key) {
     return getSpecificScope(null);
   }
 
+  private <T> @NotNull T getDefaultScopeValue(
+      final @NotNull T globalValue,
+      final @NotNull T isolationValue,
+      final @NotNull T currentValue) {
+    switch (getOptions().getDefaultScopeType()) {
+      case CURRENT:
+        return currentValue;
+      case ISOLATION:
+        return isolationValue;
+      case GLOBAL:
+        return globalValue;
+      default:
+        // calm the compiler
+        return currentValue;
+    }
+  }
+
   IScope getSpecificScope(final @Nullable ScopeType scopeType) {
     if (scopeType != null) {
       switch (scopeType) {
@@ -373,10 +475,31 @@ IScope getSpecificScope(final @Nullable ScopeType scopeType) {
 
   @Override
   public @NotNull List<Attachment> getAttachments() {
+    final @NotNull List<Attachment> globalAttachments = globalScope.getAttachments();
+    final @NotNull List<Attachment> isolationAttachments = isolationScope.getAttachments();
+    final @NotNull List<Attachment> currentAttachments = scope.getAttachments();
+
+    final boolean hasGlobalAttachments = !globalAttachments.isEmpty();
+    final boolean hasIsolationAttachments = !isolationAttachments.isEmpty();
+    final boolean hasCurrentAttachments = !currentAttachments.isEmpty();
+
+    if (!hasGlobalAttachments && !hasIsolationAttachments && !hasCurrentAttachments) {
+      return getDefaultScopeValue(globalAttachments, isolationAttachments, currentAttachments);
+    }
+    if (!hasIsolationAttachments && !hasCurrentAttachments) {
+      return globalAttachments;
+    }
+    if (!hasGlobalAttachments && !hasCurrentAttachments) {
+      return isolationAttachments;
+    }
+    if (!hasGlobalAttachments && !hasIsolationAttachments) {
+      return currentAttachments;
+    }
+
     final @NotNull List<Attachment> allAttachments = new CopyOnWriteArrayList<>();
-    allAttachments.addAll(globalScope.getAttachments());
-    allAttachments.addAll(isolationScope.getAttachments());
-    allAttachments.addAll(scope.getAttachments());
+    allAttachments.addAll(globalAttachments);
+    allAttachments.addAll(isolationAttachments);
+    allAttachments.addAll(currentAttachments);
     return allAttachments;
   }
 
diff --git a/sentry/src/main/java/io/sentry/JsonSerializer.java b/sentry/src/main/java/io/sentry/JsonSerializer.java
index 2b24090d0c..79a1c72bef 100644
--- a/sentry/src/main/java/io/sentry/JsonSerializer.java
+++ b/sentry/src/main/java/io/sentry/JsonSerializer.java
@@ -64,6 +64,8 @@ public final class JsonSerializer implements ISerializer {
   @SuppressWarnings("CharsetObjectCanBeUsed")
   private static final Charset UTF_8 = Charset.forName("UTF-8");
 
+  private static final int WRITER_BUFFER_SIZE = 512;
+
   /** the SentryOptions */
   private final @NotNull SentryOptions options;
 
@@ -233,7 +235,8 @@ public void serialize(@NotNull SentryEnvelope envelope, @NotNull OutputStream ou
 
     // we do not want to close these as we would also close the stream that was passed in
     final BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(outputStream);
-    final Writer writer = new BufferedWriter(new OutputStreamWriter(bufferedOutputStream, UTF_8));
+    final Writer writer =
+        new BufferedWriter(new OutputStreamWriter(bufferedOutputStream, UTF_8), WRITER_BUFFER_SIZE);
 
     try {
       envelope
diff --git a/sentry/src/main/java/io/sentry/MainEventProcessor.java b/sentry/src/main/java/io/sentry/MainEventProcessor.java
index 8c684bfb65..d84c9e47be 100644
--- a/sentry/src/main/java/io/sentry/MainEventProcessor.java
+++ b/sentry/src/main/java/io/sentry/MainEventProcessor.java
@@ -11,7 +11,6 @@
 import java.io.Closeable;
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import org.jetbrains.annotations.ApiStatus;
@@ -191,7 +190,7 @@ private void setSdk(final @NotNull SentryBaseEvent event) {
 
   private void setTags(final @NotNull SentryBaseEvent event) {
     if (event.getTags() == null) {
-      event.setTags(new HashMap<>(options.getTags()));
+      event.setTags(options.getTags());
     } else {
       for (Map.Entry<String, String> item : options.getTags().entrySet()) {
         if (!event.getTags().containsKey(item.getKey())) {
diff --git a/sentry/src/main/java/io/sentry/SentryClient.java b/sentry/src/main/java/io/sentry/SentryClient.java
index 78225f05d1..a739eddd9d 100644
--- a/sentry/src/main/java/io/sentry/SentryClient.java
+++ b/sentry/src/main/java/io/sentry/SentryClient.java
@@ -27,7 +27,6 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import org.jetbrains.annotations.ApiStatus;
@@ -1425,7 +1424,7 @@ public void captureBatchedMetricsEvents(final @NotNull SentryMetricsEvents metri
       event.setUser(scope.getUser());
     }
     if (event.getTags() == null) {
-      event.setTags(new HashMap<>(scope.getTags()));
+      event.setTags(scope.getTags());
     } else {
       for (Map.Entry<String, String> item : scope.getTags().entrySet()) {
         if (!event.getTags().containsKey(item.getKey())) {
@@ -1483,7 +1482,7 @@ public void captureBatchedMetricsEvents(final @NotNull SentryMetricsEvents metri
         replayEvent.setUser(scope.getUser());
       }
       if (replayEvent.getTags() == null) {
-        replayEvent.setTags(new HashMap<>(scope.getTags()));
+        replayEvent.setTags(scope.getTags());
       } else {
         for (Map.Entry<String, String> item : scope.getTags().entrySet()) {
           if (!replayEvent.getTags().containsKey(item.getKey())) {
@@ -1523,7 +1522,7 @@ public void captureBatchedMetricsEvents(final @NotNull SentryMetricsEvents metri
         sentryBaseEvent.setUser(scope.getUser());
       }
       if (sentryBaseEvent.getTags() == null) {
-        sentryBaseEvent.setTags(new HashMap<>(scope.getTags()));
+        sentryBaseEvent.setTags(scope.getTags());
       } else {
         for (Map.Entry<String, String> item : scope.getTags().entrySet()) {
           if (!sentryBaseEvent.getTags().containsKey(item.getKey())) {
@@ -1537,7 +1536,7 @@ public void captureBatchedMetricsEvents(final @NotNull SentryMetricsEvents metri
         sortBreadcrumbsByDate(sentryBaseEvent, scope.getBreadcrumbs());
       }
       if (sentryBaseEvent.getExtras() == null) {
-        sentryBaseEvent.setExtras(new HashMap<>(scope.getExtras()));
+        sentryBaseEvent.setExtras(scope.getExtras());
       } else {
         for (Map.Entry<String, Object> item : scope.getExtras().entrySet()) {
           if (!sentryBaseEvent.getExtras().containsKey(item.getKey())) {
diff --git a/sentry/src/main/java/io/sentry/SentryEnvelopeItem.java b/sentry/src/main/java/io/sentry/SentryEnvelopeItem.java
index dbbc36524d..728478f590 100644
--- a/sentry/src/main/java/io/sentry/SentryEnvelopeItem.java
+++ b/sentry/src/main/java/io/sentry/SentryEnvelopeItem.java
@@ -41,6 +41,8 @@ public final class SentryEnvelopeItem {
   @SuppressWarnings("CharsetObjectCanBeUsed")
   private static final Charset UTF_8 = Charset.forName("UTF-8");
 
+  private static final int WRITER_BUFFER_SIZE = 512;
+
   private final SentryEnvelopeItemHeader header;
   // Either dataFactory is set or data needs to be set.
   private final @Nullable Callable<byte[]> dataFactory;
@@ -85,7 +87,9 @@ public final class SentryEnvelopeItem {
         new CachedItem(
             () -> {
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(session, writer);
                 return stream.toByteArray();
               }
@@ -119,7 +123,9 @@ public final class SentryEnvelopeItem {
         new CachedItem(
             () -> {
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(event, writer);
                 return stream.toByteArray();
               }
@@ -179,7 +185,9 @@ public static SentryEnvelopeItem fromUserFeedback(
         new CachedItem(
             () -> {
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(userFeedback, writer);
                 return stream.toByteArray();
               }
@@ -206,7 +214,9 @@ public static SentryEnvelopeItem fromCheckIn(
         new CachedItem(
             () -> {
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(checkIn, writer);
                 return stream.toByteArray();
               }
@@ -344,7 +354,9 @@ private static void ensureAttachmentSizeLimit(
               }
 
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(profileChunk, writer);
                 return stream.toByteArray();
               } catch (IOException e) {
@@ -403,7 +415,9 @@ private static void ensureAttachmentSizeLimit(
               profilingTraceData.readDeviceCpuFrequencies();
 
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(profilingTraceData, writer);
                 return stream.toByteArray();
               } catch (IOException e) {
@@ -437,7 +451,9 @@ private static void ensureAttachmentSizeLimit(
         new CachedItem(
             () -> {
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(clientReport, writer);
                 return stream.toByteArray();
               }
@@ -481,7 +497,8 @@ public static SentryEnvelopeItem fromReplay(
               try {
                 try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
                     final Writer writer =
-                        new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                        new BufferedWriter(
+                            new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                   // relay expects the payload to be in this exact order: [event,rrweb,video]
                   final Map<String, byte[]> replayPayload = new LinkedHashMap<>();
                   // first serialize replay event json bytes
@@ -541,7 +558,9 @@ public static SentryEnvelopeItem fromLogs(
         new CachedItem(
             () -> {
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(logEvents, writer);
                 return stream.toByteArray();
               }
@@ -571,7 +590,9 @@ public static SentryEnvelopeItem fromMetrics(
         new CachedItem(
             () -> {
               try (final ByteArrayOutputStream stream = new ByteArrayOutputStream();
-                  final Writer writer = new BufferedWriter(new OutputStreamWriter(stream, UTF_8))) {
+                  final Writer writer =
+                      new BufferedWriter(
+                          new OutputStreamWriter(stream, UTF_8), WRITER_BUFFER_SIZE)) {
                 serializer.serialize(metricsEvents, writer);
                 return stream.toByteArray();
               }
diff --git a/sentry/src/test/java/io/sentry/CombinedScopeViewTest.kt b/sentry/src/test/java/io/sentry/CombinedScopeViewTest.kt
index d768d6d32d..fd187235a9 100644
--- a/sentry/src/test/java/io/sentry/CombinedScopeViewTest.kt
+++ b/sentry/src/test/java/io/sentry/CombinedScopeViewTest.kt
@@ -11,6 +11,7 @@ import junit.framework.TestCase.assertTrue
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
+import kotlin.test.assertNotSame
 import kotlin.test.assertNull
 import kotlin.test.assertSame
 import org.junit.Assert.assertNotEquals
@@ -72,6 +73,74 @@ class CombinedScopeViewTest {
     assertEquals("current 2", breadcrumbs.poll().message)
   }
 
+  @Test
+  fun `returns single non-empty breadcrumb queue directly`() {
+    var combined = fixture.getSut()
+    fixture.globalScope.addBreadcrumb(Breadcrumb.info("global"))
+    assertSame(fixture.globalScope.breadcrumbs, combined.breadcrumbs)
+
+    combined = fixture.getSut()
+    fixture.isolationScope.addBreadcrumb(Breadcrumb.info("isolation"))
+    assertSame(fixture.isolationScope.breadcrumbs, combined.breadcrumbs)
+
+    combined = fixture.getSut()
+    fixture.scope.addBreadcrumb(Breadcrumb.info("current"))
+    assertSame(fixture.scope.breadcrumbs, combined.breadcrumbs)
+  }
+
+  @Test
+  fun `returns default write scope breadcrumbs when all scopes are empty`() {
+    val combined = fixture.getSut(SentryOptions().also { it.defaultScopeType = ScopeType.CURRENT })
+
+    assertSame(fixture.scope.breadcrumbs, combined.breadcrumbs)
+  }
+
+  @Test
+  fun `returns merged breadcrumb copy when multiple scopes have breadcrumbs`() {
+    val combined = fixture.getSut()
+
+    fixture.globalScope.addBreadcrumb(Breadcrumb.info("global"))
+    fixture.isolationScope.addBreadcrumb(Breadcrumb.info("isolation"))
+
+    val breadcrumbs = combined.breadcrumbs
+
+    assertNotSame(fixture.globalScope.breadcrumbs, breadcrumbs)
+    assertNotSame(fixture.isolationScope.breadcrumbs, breadcrumbs)
+    assertEquals(2, breadcrumbs.size)
+  }
+
+  @Test
+  fun `returns single non-empty combined collections directly`() {
+    val globalScope = mock<IScope>()
+    val isolationScope = mock<IScope>()
+    val scope = mock<IScope>()
+    val combined = CombinedScopeView(globalScope, isolationScope, scope)
+
+    val tags = mapOf("tag" to "value")
+    whenever(globalScope.tags).thenReturn(emptyMap())
+    whenever(isolationScope.tags).thenReturn(emptyMap())
+    whenever(scope.tags).thenReturn(tags)
+    assertSame(tags, combined.tags)
+
+    val attributes = mapOf("attribute" to SentryAttribute.named("attribute", "value"))
+    whenever(globalScope.attributes).thenReturn(emptyMap())
+    whenever(isolationScope.attributes).thenReturn(emptyMap())
+    whenever(scope.attributes).thenReturn(attributes)
+    assertSame(attributes, combined.attributes)
+
+    val extras = mapOf<String, Any>("extra" to "value")
+    whenever(globalScope.extras).thenReturn(emptyMap())
+    whenever(isolationScope.extras).thenReturn(emptyMap())
+    whenever(scope.extras).thenReturn(extras)
+    assertSame(extras, combined.extras)
+
+    val attachments = listOf(createAttachment("attachment.png"))
+    whenever(globalScope.attachments).thenReturn(emptyList())
+    whenever(isolationScope.attachments).thenReturn(emptyList())
+    whenever(scope.attachments).thenReturn(attachments)
+    assertSame(attachments, combined.attachments)
+  }
+
   @Test
   fun `oldest breadcrumbs are dropped first`() {
     val options = SentryOptions().also { it.maxBreadcrumbs = 5 }
diff --git a/sentry/src/test/java/io/sentry/MainEventProcessorTest.kt b/sentry/src/test/java/io/sentry/MainEventProcessorTest.kt
index 229fd57187..fe5c835c90 100644
--- a/sentry/src/test/java/io/sentry/MainEventProcessorTest.kt
+++ b/sentry/src/test/java/io/sentry/MainEventProcessorTest.kt
@@ -358,6 +358,19 @@ class MainEventProcessorTest {
     }
   }
 
+  @Test
+  fun `options tags are copied when applied to event`() {
+    val sut = fixture.getSut(tags = mapOf("tag1" to "value1"))
+    val event = SentryEvent()
+
+    sut.process(event, Hint())
+    val eventTags = event.tags!!
+
+    fixture.sentryOptions.setTag("tag2", "value2")
+
+    assertFalse(eventTags.containsKey("tag2"))
+  }
+
   @Test
   fun `when event has a tag set with the same name as SentryOptions tags, the tag value from the event is retained`() {
     val sut = fixture.getSut(tags = mapOf("tag1" to "value1", "tag2" to "value2"))
diff --git a/sentry/src/test/java/io/sentry/SentryClientTest.kt b/sentry/src/test/java/io/sentry/SentryClientTest.kt
index ab6fd2075a..f51345957e 100644
--- a/sentry/src/test/java/io/sentry/SentryClientTest.kt
+++ b/sentry/src/test/java/io/sentry/SentryClientTest.kt
@@ -534,6 +534,24 @@ class SentryClientTest {
     assertNotNull(event.request) { assertEquals("post", it.method) }
   }
 
+  @Test
+  fun `when captureEvent applies scope tags and extras, event map containers are copied`() {
+    val event = SentryEvent()
+    val scope = createScope()
+
+    val sut = fixture.getSut()
+
+    sut.captureEvent(event, scope)
+    val eventTags = event.tags!!
+    val eventExtras = event.extras!!
+
+    scope.setTag("newTag", "newValue")
+    scope.setExtra("newExtra", "newValue")
+
+    assertFalse(eventTags.containsKey("newTag"))
+    assertFalse(eventExtras.containsKey("newExtra"))
+  }
+
   @Test
   fun `when breadcrumbs are not empty, sort them out by date`() {
     val b1 = Breadcrumb(DateUtils.getDateTime("2020-03-27T08:52:58.001Z"))
diff --git a/sentry/src/test/java/io/sentry/protocol/SentryBaseEventSerializationTest.kt b/sentry/src/test/java/io/sentry/protocol/SentryBaseEventSerializationTest.kt
index 4cafb1ed8a..35322d2659 100644
--- a/sentry/src/test/java/io/sentry/protocol/SentryBaseEventSerializationTest.kt
+++ b/sentry/src/test/java/io/sentry/protocol/SentryBaseEventSerializationTest.kt
@@ -9,6 +9,7 @@ import io.sentry.SentryBaseEvent
 import io.sentry.SentryIntegrationPackageStorage
 import io.sentry.vendor.gson.stream.JsonToken
 import kotlin.test.assertEquals
+import kotlin.test.assertFalse
 import org.junit.After
 import org.junit.Before
 import org.junit.Test
@@ -102,4 +103,26 @@ class SentryBaseEventSerializationTest {
 
     assertEquals(expectedJson, actualJson)
   }
+
+  @Test
+  fun `setTags copies source map`() {
+    val source = mutableMapOf("a" to "1")
+    val sut = Sut()
+
+    sut.tags = source
+    source["b"] = "2"
+
+    assertFalse(sut.tags!!.containsKey("b"))
+  }
+
+  @Test
+  fun `setExtras copies source map`() {
+    val source = mutableMapOf<String, Any>("a" to "1")
+    val sut = Sut()
+
+    sut.setExtras(source)
+    source["b"] = "2"
+
+    assertFalse(sut.extras!!.containsKey("b"))
+  }
 }