diff --git a/.claude/rules/sim-components.md b/.claude/rules/sim-components.md
index 78b8f127a68..51090d2fb2a 100644
--- a/.claude/rules/sim-components.md
+++ b/.claude/rules/sim-components.md
@@ -12,3 +12,21 @@ Component authoring rules — structure order (refs → external hooks → store
 - `'use client'` only when using React hooks or browser-only APIs.
 - Prefer semantic HTML (`aside`, `nav`, `article`).
 - Optional-chain callbacks: `onAction?.(id)`.
+
+## List-render performance
+
+When rendering or sorting a list of rows against a lookup collection (members, folders, tags), keep the per-row work O(1):
+
+- **Precompute a lookup `Map` once**, never `array.find(...)` per row. Build `const byId = useMemo(() => { const m = new Map<string, T>(); for (const x of items ?? []) m.set(x.id, x); return m }, [items])` and read `byId.get(id)` in the sort comparator, `.map(...)`, and cell builders. A `.find` inside a sort comparator is O(n²·log n) — the worst offender. Depend memos on the derived `Map`, not the raw array.
+- **Sort with `[...array].sort(cmp)` in client code — NOT `array.toSorted(cmp)`.** SWC (Next's compiler) transforms syntax but does not polyfill prototype methods, and the repo sets no core-js/browserslist target, so `toSorted`/`toReversed`/`toSpliced`/`Array.prototype.with` ship as-is and throw `TypeError` on Safari <16 / iOS 15 (they landed in Safari 16). `tsconfig` `lib: ES2023` only affects type-checking, never the runtime. The `[...arr].sort()` spread copy is the intended cost — it keeps the sort non-mutating without an unpolyfilled builtin. These methods are only safe in server-only modules (no `'use client'`, executed on Node ≥20). react-doctor's `js-tosorted-immutable` is therefore a won't-fix in client components.
+- **Partition in a single pass** — when splitting one collection into several (`fileIds`/`folderIds`), do one `for…of` pushing into each bucket and return `{ a, b }` from a single `useMemo`, not two memos that each `map→filter→map` the same source twice.
+
+## react-doctor (`npx react-doctor`) — apply the wins, skip the false positives
+
+react-doctor diagnostics are hypotheses, not verdicts — confirm against the code before acting, and preserve behavior. Known repo-specific false positives to NOT "fix":
+
+- `no-barrel-import` — barrel imports are the repo convention (see sim-imports.md, "Barrel Exports"). Keep them.
+- `js-tosorted-immutable` — in `'use client'` code, keep `[...arr].sort(cmp)`; `toSorted` is unpolyfilled and crashes Safari <16 / iOS 15 (see "List-render performance" above). Only apply it in server-only modules.
+- `rerender-state-only-in-handlers` / "state set but never rendered" — a false positive when the `useState` is consumed by a `useEffect`/`useLayoutEffect` dependency (the effect must re-run on change). Only convert to a ref when nothing reads the value reactively.
+- `async-await-in-loop` on an upload/progress loop where sequential execution is intentional (per-item progress, server backpressure) — leave it.
+- Broad refactors (`prefer-useReducer` for many `useState`, `no-giant-component` splits) — out of scope for a perf pass; note, don't churn.
diff --git a/apps/sim/app/workspace/[workspaceId]/components/resource/components/owner-cell/owner-cell.tsx b/apps/sim/app/workspace/[workspaceId]/components/resource/components/owner-cell/owner-cell.tsx
index 3df02cde797..23a845af1b6 100644
--- a/apps/sim/app/workspace/[workspaceId]/components/resource/components/owner-cell/owner-cell.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/components/resource/components/owner-cell/owner-cell.tsx
@@ -29,15 +29,20 @@ const OwnerAvatar = memo(function OwnerAvatar({ name, image }: OwnerAvatarProps)
 /**
  * Resolves a user ID into a ResourceCell with an avatar icon and display name.
  * Returns null label while members are still loading to avoid flashing raw IDs.
+ *
+ * Accepts either the raw member array or a precomputed `userId → member` map.
+ * Prefer the map form when resolving many rows so lookups stay O(1) instead of
+ * scanning the array per row.
  */
 export function ownerCell(
   userId: string | null | undefined,
-  members?: WorkspaceMember[]
+  members?: WorkspaceMember[] | Map<string, WorkspaceMember>
 ): ResourceCell {
   if (!userId) return { label: null }
   if (!members) return { label: null }
 
-  const member = members.find((m) => m.userId === userId)
+  const member =
+    members instanceof Map ? members.get(userId) : members.find((m) => m.userId === userId)
   if (!member) return { label: null }
 
   return {
diff --git a/apps/sim/app/workspace/[workspaceId]/files/files.tsx b/apps/sim/app/workspace/[workspaceId]/files/files.tsx
index cbc9828cd53..e8be45d8fa6 100644
--- a/apps/sim/app/workspace/[workspaceId]/files/files.tsx
+++ b/apps/sim/app/workspace/[workspaceId]/files/files.tsx
@@ -78,7 +78,7 @@ import type { MoveOptionNode } from '@/app/workspace/[workspaceId]/files/move-op
 import { filesParsers, filesUrlKeys } from '@/app/workspace/[workspaceId]/files/search-params'
 import { useUserPermissionsContext } from '@/app/workspace/[workspaceId]/providers/workspace-permissions-provider'
 import { useContextMenu } from '@/app/workspace/[workspaceId]/w/components/sidebar/hooks'
-import { useWorkspaceMembersQuery } from '@/hooks/queries/workspace'
+import { useWorkspaceMembersQuery, type WorkspaceMember } from '@/hooks/queries/workspace'
 import {
   useBulkArchiveWorkspaceFileItems,
   useCreateWorkspaceFileFolder,
@@ -197,6 +197,11 @@ export function Files() {
   const { data: files = EMPTY_WORKSPACE_FILES, isLoading, error } = useWorkspaceFiles(workspaceId)
   const { data: folders = EMPTY_WORKSPACE_FILE_FOLDERS } = useWorkspaceFileFolders(workspaceId)
   const { data: members } = useWorkspaceMembersQuery(workspaceId)
+  const membersById = useMemo(() => {
+    const map = new Map<string, WorkspaceMember>()
+    for (const member of members ?? []) map.set(member.userId, member)
+    return map
+  }, [members])
   const uploadFile = useUploadWorkspaceFile()
   const notifyLimit = useLimitUpgradeToast()
   const deleteFile = useDeleteWorkspaceFile()
@@ -416,8 +421,8 @@ export function Files() {
           cmp = new Date(a.updatedAt).getTime() - new Date(b.updatedAt).getTime()
           break
         case 'owner':
-          cmp = (members?.find((m) => m.userId === a.uploadedBy)?.name ?? '').localeCompare(
-            members?.find((m) => m.userId === b.uploadedBy)?.name ?? ''
+          cmp = (membersById.get(a.uploadedBy)?.name ?? '').localeCompare(
+            membersById.get(b.uploadedBy)?.name ?? ''
           )
           break
       }
@@ -431,7 +436,7 @@ export function Files() {
     sizeFilter,
     uploadedByFilter,
     activeSort,
-    members,
+    membersById,
   ])
 
   const baseRows: ResourceRow[] = useMemo(() => {
@@ -453,7 +458,7 @@ export function Files() {
           label: 'Folder',
         },
         created: timeCell(folder.createdAt),
-        owner: ownerCell(folder.userId, members),
+        owner: ownerCell(folder.userId, membersById),
         updated: timeCell(folder.updatedAt),
       },
     }))
@@ -475,7 +480,7 @@ export function Files() {
             label: formatFileType(file.type, file.name),
           },
           created: timeCell(file.uploadedAt),
-          owner: ownerCell(file.uploadedBy, members),
+          owner: ownerCell(file.uploadedBy, membersById),
           updated: timeCell(file.updatedAt),
         },
       }
@@ -483,7 +488,7 @@ export function Files() {
     })
 
     return [...folderRows, ...fileRows]
-  }, [visibleFolders, filteredFiles, members, folderSizeMap])
+  }, [visibleFolders, filteredFiles, membersById, folderSizeMap])
 
   const rows: ResourceRow[] = useMemo(() => {
     if (!listRename.editingId) return baseRows
@@ -525,22 +530,16 @@ export function Files() {
 
   const isAllSelected =
     visibleRowIds.length > 0 && visibleRowIds.every((id) => selectedRowIds.has(id))
-  const selectedFileIds = useMemo(
-    () =>
-      Array.from(selectedRowIds)
-        .map(parseRowId)
-        .filter((item) => item.kind === 'file')
-        .map((item) => item.id),
-    [selectedRowIds]
-  )
-  const selectedFolderIds = useMemo(
-    () =>
-      Array.from(selectedRowIds)
-        .map(parseRowId)
-        .filter((item) => item.kind === 'folder')
-        .map((item) => item.id),
-    [selectedRowIds]
-  )
+  const { selectedFileIds, selectedFolderIds } = useMemo(() => {
+    const fileIds: string[] = []
+    const folderIds: string[] = []
+    for (const rowId of selectedRowIds) {
+      const item = parseRowId(rowId)
+      if (item.kind === 'file') fileIds.push(item.id)
+      else folderIds.push(item.id)
+    }
+    return { selectedFileIds: fileIds, selectedFolderIds: folderIds }
+  }, [selectedRowIds])
 
   const selectableConfig = useMemo(
     () => ({
@@ -1749,7 +1748,7 @@ export function Files() {
       uploadedByFilter.length === 0
         ? 'All'
         : uploadedByFilter.length === 1
-          ? (members?.find((m) => m.userId === uploadedByFilter[0])?.name ?? '1 member')
+          ? (membersById.get(uploadedByFilter[0])?.name ?? '1 member')
           : `${uploadedByFilter.length} members`
 
     return (
@@ -1831,7 +1830,7 @@ export function Files() {
         )}
       </div>
     )
-  }, [typeFilter, sizeFilter, uploadedByFilter, memberOptions, members, hasActiveFilters])
+  }, [typeFilter, sizeFilter, uploadedByFilter, memberOptions, membersById, hasActiveFilters])
 
   const filterTags: FilterTag[] = useMemo(() => {
     const tags: FilterTag[] = []
@@ -1863,12 +1862,12 @@ export function Files() {
     if (uploadedByFilter.length > 0) {
       const label =
         uploadedByFilter.length === 1
-          ? `Uploaded by: ${members?.find((m) => m.userId === uploadedByFilter[0])?.name ?? '1 member'}`
+          ? `Uploaded by: ${membersById.get(uploadedByFilter[0])?.name ?? '1 member'}`
           : `Uploaded by: ${uploadedByFilter.length} members`
       tags.push({ label, onRemove: () => setUploadedByFilter([]) })
     }
     return tags
-  }, [typeFilter, sizeFilter, uploadedByFilter, members])
+  }, [typeFilter, sizeFilter, uploadedByFilter, membersById])
 
   if (fileIdFromRoute && !selectedFile && isLoading) {
     return (