Mobile Engineering

Performance & Memory

6 practice questions. Free questions open a full answer guide; the rest unlock with Pro.

  • Why is it important to keep heavy work off the main thread in a mobile app, and what kinds of work belong on a background thread? Junior level
  • An app feels janky when scrolling a feed. How do you diagnose where the dropped frames are coming from, and what are the usual culprits?Go Pro Mid level
  • How would you load large images in a scrolling list without running out of memory or making the list stutter?Go Pro Junior level
  • Your app's cold start feels fine on your test device but users on mid-range phones report a multi-second blank screen on launch. How do you reason about what's happening before the first frame and where to cut?Go Pro Senior level
  • A list screen scrolls smoothly on a flagship but stutters and occasionally gets killed for memory on cheaper devices. How do you diagnose whether it's a memory problem, a frame-budget problem, or both, and fix it?Go Pro Senior level
  • Your app's cold start is too slow and you're seeing drop-off before the first screen. How do you think about reducing launch time?Go Pro Mid level
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