LESSON 03 / 9·2 min readIntermediate

How do I check performance?

01 Understand02 Recall03 Prepare

Understand the concept

A performance review checks whether the amount of work stays reasonable as input size and traffic increase. Database calls, large allocations and synchronous CPU work can be more important than small syntax choices. Use measurements for suspected hotspots rather than adding optimizations everywhere.

Important ideas

  • Look for queries in loops, unbounded lists and CPU-heavy synchronous work.

  • Inspect generated SQL, query plans and selected fields.

  • Measure before adding caching or memoization.

  • Estimate query count for one request with 100 items and consider whether every selected field is actually used.

PAUSE & RECALL

Can you explain it without the notes?

How do I check performance?

Use your own words. Explain an example and one limitation before checking the explanation.

Check your explanation

A performance review checks whether the amount of work stays reasonable as input size and traffic increase. Database calls, large allocations and synchronous CPU work can be more important than small syntax choices. Use measurements for suspected hotspots rather than adding optimizations everywhere.

CONNECT IT TO YOUR INTERVIEW

Turn this concept into a clear answer.

  • Explain how the cost grows and which resource becomes constrained, then propose a measurable fix.
Practice this concept
YOUR NEXT STEP

Keep connecting the ideas.

Next lesson: How do I check reliability?

Adapted from 11_AI_CODE_REVIEW.md · “How do I check performance?”. Examples are study fragments; framework behavior can depend on your version.