Performance Interview Questions 2026
Published July 22, 2026 · Updated July 22, 2026
12 Performance interview questions from Accenture, PayU, Apple, Adobe. All difficulty levels, all roles. Upvoted by engineers who were asked them.
12 questions
Companies: Accenture, PayU, Apple, Adobe
612 upvotes
Performance Questions by Company
Accenture (8)
Accenture
Medium
Technical round
8–12 YearsReactCSSPerformance
What is Critical CSS, and how does it improve page load performance in React applications?
↑ 37 upvotes · 24 engineers asked this · Full Stack Developer
Accenture
Medium
Technical round
8–12 YearsReactNext.jsPerformance
What techniques can be used to optimize images in React or Next.js applications for better performance?
↑ 52 upvotes · 35 engineers asked this · Full Stack Developer
Accenture
Hard
Technical round
8–12 YearsReactJavaScriptPerformance
What causes unnecessary re-renders in React, and how can React.memo, useMemo, and useCallback help improve performance?
↑ 78 upvotes · 54 engineers asked this · Full Stack Developer
Accenture
Medium
Technical round
8–12 YearsHTMLJavaScriptPerformance
What are resource hints such as preload, prefetch, and dns-prefetch? Explain when you would use each of them.
↑ 45 upvotes · 31 engineers asked this · Full Stack Developer
Accenture
Hard
Technical round
8–12 YearsReactWebpackPerformance
A React application has a slow initial page load. What steps would you take to identify and fix the performance bottlenecks?
↑ 67 upvotes · 47 engineers asked this · Full Stack Developer
Accenture
Medium
Technical round
8–12 YearsJavaScriptReactPerformance
How would you optimize the loading of third-party scripts such as analytics, chat widgets, or advertising libraries?
↑ 49 upvotes · 33 engineers asked this · Full Stack Developer
Accenture
Hard
Technical round
8–12 YearsReactLighthousePerformance
What strategies would you use to improve Core Web Vitals (LCP, FID/INP, CLS) in a React application?
↑ 71 upvotes · 49 engineers asked this · Full Stack Developer
Accenture
Hard
Technical round
8–12 YearsReactJavaScriptPerformance
A component renders hundreds of items and users experience UI lag. How would you investigate and optimize the rendering performance?
↑ 63 upvotes · 44 engineers asked this · Full Stack Developer
PayU (1)
PayU
Hard
Technical round
2–5 YearsInterview ExperienceJavaScriptReactPerformance
A merchant reports that their checkout page built with your SDK scores 38 on Google Lighthouse. Walk through your systematic debugging process: which Core Web Vitals are likely failing, what tools you would use, and give five concrete optimisations specific to a payment checkout flow.
↑ 79 upvotes · 56 engineers asked this · Full Stack Developer
Apple (2)
Apple
Hard
Technical round
3-7 yearsPerformanceiOS
An iOS app's scroll performance drops to visibly janky frame rates on a list with complex cells. Walk through your process for diagnosing whether the bottleneck is layout, rendering, or data processing.
↑ 29 upvotes · 10 engineers asked this · Senior SDE
Apple
Medium
Technical round
3-7 yearsPerformance
An app's cold launch time regressed from 800ms to 1.4s after a release. What's your systematic approach to finding the regression before assuming which commit caused it?
↑ 21 upvotes · 10 engineers asked this · Senior SDE
Adobe (1)
Adobe
Medium
Technical round
2-6 yearsPerformanceJavaScript
A web-based PDF viewer becomes unresponsive when rendering a 200-page document. What rendering strategy would you use so the app stays responsive?
↑ 21 upvotes · 7 engineers asked this · Senior SDE
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Performance questions at each company
Frequently asked questions
What is Critical CSS, and how does it improve page load performance in React applications?
What is Critical CSS, and how does it improve page load performance in React applications?
What techniques can be used to optimize images in React or Next.js applications for better performance?
What techniques can be used to optimize images in React or Next.js applications for better performance?
What causes unnecessary re-renders in React, and how can React.memo, useMemo, and useCallback help improve performance?
What causes unnecessary re-renders in React, and how can React.memo, useMemo, and useCallback help improve performance?
What are resource hints such as preload, prefetch, and dns-prefetch? Explain when you would use each of them.
What are resource hints such as preload, prefetch, and dns-prefetch? Explain when you would use each of them.
A React application has a slow initial page load. What steps would you take to identify and fix the performance bottlenecks?
A React application has a slow initial page load. What steps would you take to identify and fix the performance bottlenecks?