AI Prompts for Cursor for Performance Optimization

My application is slow in [DESCRIBE WHERE: PAGE LOAD / API RESPONSE / SPECIFIC FUNCTION]. Help me instrument the code to find the bottleneck: [PASTE CODE]. What should I measure and how?

Write code to measure the performance of this function: [PASTE FUNCTION]. Use [CONSOLE.TIME / PERFORMANCE.NOW / THE APPROPRIATE PROFILING TOOL FOR MY LANGUAGE]. Show how to log results.

This API route is responding too slowly: [PASTE ROUTE HANDLER]. Walk me through how to profile it: timing each database call, each computation, and each external call to find where the time is going.

Help me interpret this performance profile output: [PASTE PROFILE RESULTS]. What are the hottest functions? What should I optimize first based on time spent and call frequency?

Help me set realistic performance targets for [TYPE OF APP: WEB APP / API / CLI]. What are good benchmarks for [PAGE LOAD TIME / API LATENCY / FUNCTION EXECUTION TIME] based on current best practices?

This code is O(n²) or worse due to nested loops: [PASTE CODE]. Rewrite it to be more efficient. Explain the complexity of the original and the improved version.

I'm using [ARRAY / OBJECT / SET / MAP] for [DESCRIBE THE OPERATION]. Am I using the right data structure for this use case? What is the time complexity of my current operations and what should I use instead?

This code is computing the same value multiple times: [PASTE CODE]. Refactor to compute it once and reuse the result. Add memoization if it is called repeatedly with the same inputs.

This code does a lot of string operations that are slow: [PASTE CODE]. Rewrite to use more efficient string handling: string builders, avoiding repeated concatenation, or batch operations.

Add memoization or caching to this function that is called repeatedly with the same inputs: [PASTE FUNCTION]. Use [SIMPLE OBJECT CACHE / LRU CACHE / REDIS] and handle cache invalidation.

These async operations run sequentially but could run in parallel: [PASTE CODE]. Rewrite using Promise.all or equivalent to run them concurrently. Show the time savings.

I have an N+1 query problem: [PASTE CODE SHOWING THE LOOP WITH A QUERY INSIDE]. Rewrite to fetch all needed data in one or two queries using JOINs, batch fetching, or DataLoader.

These database queries are slow: [PASTE QUERIES]. What indexes should I add? Show the CREATE INDEX statements and explain how each index helps the specific query.

This code loads a large dataset into memory at once: [PASTE CODE]. Rewrite it to process the data as a stream so memory usage stays flat even for large datasets.

My code makes an API call for each item in a loop: [PASTE CODE]. Rewrite it to batch the API calls, using the API's batch endpoint if available, or processing in chunks of [N] items.

Analyze this code for bundle size optimizations: [PASTE IMPORTS AND CODE]. Identify: unused imports, large libraries with lighter alternatives, and code that should be lazy-loaded.

This React component re-renders too often: [PASTE COMPONENT]. Identify the causes and fix them using: React.memo, useMemo, useCallback, or state restructuring.

Help me improve [LCP / CLS / INP / FID] for this page: [DESCRIBE OR PASTE THE PAGE CODE]. What are the most impactful changes I can make to improve this specific metric?

Review the image loading in this page: [PASTE CODE]. Suggest: correct image formats, lazy loading, proper sizing, and CDN delivery strategies to minimize image-related performance issues.

Help me identify which JavaScript, CSS, and third-party scripts in this page are non-critical: [PASTE OR DESCRIBE]. Show how to defer or lazy-load each without breaking functionality.