Cursor Performance TuningSAFE

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The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: cursor-performance-tuning
description: 'Optimize Cursor IDE performance: reduce memory usage, speed up indexing,
  tune AI features, and manage

  extensions for large codebases. Triggers on "cursor performance", "cursor slow",
  "cursor optimization",

  "cursor memory", "speed up cursor", "cursor lag".

  '
allowed-tools: Read, Write, Edit, Bash(cmd:*)
version: 1.19.0
license: MIT
author: Jeremy Longshore <[email protected]>
tags:
- saas
- cursor
- performance
compatibility: Designed for Claude Code
---
# Cursor Performance Tuning

## Overview

Improve Cursor responsiveness by measuring indexing scope, resource use, extension load, and network conditions while preserving required workspace and data controls.

## Prerequisites

- A reproducible performance symptom, baseline measurement, and approved local settings backup.
- A reviewed `.cursorignore` strategy; do not expose excluded files to gain speed.

## Instructions

1. Measure startup, indexing, memory, and request latency for the affected workspace.
2. Reduce unnecessary roots, extensions, and generated-file indexing before clearing caches.
3. Make one reversible change, compare against baseline, and retain the setting only when it improves the agreed metric.
4. Back up settings before cache maintenance and test the restored workspace afterward.

## Output

- A measured, reversible performance change with before/after evidence.

## Error Handling

| Condition | Safe response |
|---|---|
| Cache clear does not help | Restore settings and investigate extension/indexing scope rather than repeating deletion. |
| Performance requires policy exception | Keep policy intact and escalate for a documented decision. |
| Network latency is the cause | Use approved network troubleshooting; do not route code through an unapproved service. |

## Examples

For a slow monorepo, measure indexing time, add generated artifacts to the existing reviewed ignore rules, close inactive workspace roots, and measure again. Keep the change only if it improves the baseline without hiding required source or documentation.

Diagnose and fix Cursor IDE performance issues. Covers editor optimization, indexing tuning, extension auditing, AI feature configuration, and strategies for large codebases.

## Performance Diagnostic Workflow

```
Step 1: Identify bottleneck
         ├── Editor lag? → Step 2 (Editor settings)
         ├── High CPU?   → Step 3 (Extension audit)
         ├── Slow AI?    → Step 4 (AI tuning)
         └── Memory?     → Step 5 (Memory management)

Step 2: Editor settings
         ├── Disable minimap, breadcrumbs
         ├── Reduce file watcher scope
         └── Increase memory limits

Step 3: Extension audit
         ├── Profile running extensions
         ├── Disable heavy extensions
         └── Use workspace-scoped disabling

Step 4: AI feature tuning
         ├── Optimize .cursorignore
         ├── Use faster models
         └── Manage chat history

Step 5: Memory management
         ├── Close unused workspace folders
         ├── Limit open editor tabs
         └── Clear caches
```

## Editor Optimization

### settings.json Performance Settings

```json
{
  // Disable visual features for speed
  "editor.minimap.enabled": false,
  "editor.renderWhitespace": "none",
  "editor.guides.bracketPairs": false,
  "breadcrumbs.enabled": false,
  "editor.occurrencesHighlight": "off",
  "editor.matchBrackets": "never",
  "editor.folding": false,
  "editor.glyphMargin": false,

  // Reduce file watching scope
  "files.watcherExclude": {
    "**/node_modules/**": true,
    "**/.git/objects/**": true,
    "**/.git/subtree-cache/**": true,
    "**/dist/**": true,
    "**/build/**": true,
    "**/coverage/**": true,
    "**/.next/**": true,
    "**/target/**": true
  },

  // Exclude from search and explorer
  "files.exclude": {
    "**/node_modules": true,
    "**/.git": true,
    "**/dist": true,
    "**/build": true
  },

  // Memory limits
  "files.maxMemoryForLargeFilesMB": 4096,

  // Reduce auto-save overhead
  "files.autoSave": "onFocusChange",

  // Limit search results
  "search.maxResults": 5000
}
```

### Disable Animations

```json
{
  "workbench.list.smoothScrolling": false,
  "editor.smoothScrolling": false,
  "editor.cursorSmoothCaretAnimation": "off",
  "terminal.integrated.smoothScrolling": false
}
```

## Extension Audit

### Profile Running Extensions

`Cmd+Shift+P` > `Developer: Show Running Extensions`

This shows:

- Extension name
- Activation time (ms)
- Profile CPU time

Sort by activation time. Extensions taking > 500ms are worth investigating.

### Process Explorer

`Cmd+Shift+P` > `Developer: Open Process Explorer`

Shows per-process CPU and memory usage:

- Main window
- Extension host (all extensions combined)
- Individual extension processes
- Terminal processes

### Common High-Impact Extensions

| Extension | Impact | Mitigation |
|-----------|--------|------------|
| **GitLens** | CPU: high on large repos | Disable for repos > 50K commits or use lightweight mode |
| **Prettier** | CPU: triggers on every save | Set `"editor.formatOnSave": false`, format manually |
| **TypeScript** | Memory: large projects | Increase `"typescript.tsserver.maxTsServerMemory": 4096` |
| **ESLint** | CPU: validates on type | Set `"eslint.run": "onSave"` instead of "onType" |
| **Spell Checker** | CPU: large files | Add exclusion patterns for generated files |
| **Import Cost** | CPU: recalculates on change | Disable for projects with many imports |

### Disable Per Workspace

Right-click extension > `Disable (Workspace)`. This keeps the extension available for other projects while removing it from the current slow one.

## AI Feature Tuning

### Indexing Optimization

The biggest performance lever for AI features:

```gitignore
# .cursorignore -- aggressive exclusion for large projects
node_modules/
dist/
build/
.next/
out/
target/
coverage/
.turbo/
.cache/
__pycache__/
*.pyc
venv/
.venv/

# Generated code
*.min.js
*.min.css

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (0)

No findings outside the package's declared scope.

Gates applied: no_behavioural_pass.