Google Flutter Google Flutter Performance 2

Question 1

Which Flutter build mode should you always use when profiling app performance?

Accepted Answer

Profile mode

Answer

Profile mode compiles the app with AOT while keeping profiling hooks enabled, giving realistic performance numbers without debug overhead.

Question 2

What is the main benefit of using ListView.builder over ListView for large lists?

Accepted Answer

ListView.builder lazily builds only visible items, reducing memory and build time

Answer

ListView.builder constructs items on demand as they scroll into view, avoiding building all items upfront for long lists.

Question 3

How does the cached_network_image package improve Flutter app performance?

Accepted Answer

It caches downloaded images on disk and memory to avoid redundant network requests

Answer

cached_network_image stores downloaded images in a local cache, serving them instantly on repeat displays without hitting the network.

Question 4

What is the purpose of compute() in Flutter?

Accepted Answer

To run a heavy computation on a separate isolate without blocking the UI thread

Answer

compute() spawns a new isolate to run a function, keeping expensive work off the main UI thread to prevent jank.

Question 5

Which Flutter widget efficiently builds a large list where all children have the same height?

Accepted Answer

ListView.builder with itemExtent

Answer

Setting itemExtent on ListView.builder tells Flutter the exact height of each item, enabling O(1) scroll position calculations instead of layout passes.

Google Flutter Practice Test

Google Flutter Practice Test

Google Flutter Google Flutter Performance 2