Question 1

Why do we profile before optimizing Flutter performance?

Accepted Answer

Measurement identifies the stage, the device, and the costly code path instead of guessing at an optimization that may not change the user experience.

Question 2

What does frame budget mean and how do you diagnose jank?

Accepted Answer

Each frame has limited time to be built and painted; exceeding the budget causes stutter, and you must determine whether the cause is the UI thread or raster work.

Question 3

When do you use ListView.builder instead of building a whole list?

Accepted Answer

A builder creates children on demand, reducing memory and initial work for large or unbounded lists.

Question 4

How do you prevent expensive work inside build?

Accepted Answer

Compute or load data outside build, use memoization or suitable state, and reduce the subtree that is rebuilt instead of hiding the work in a helper.

Question 5

How do you explain image and memory performance problems in Flutter?

Accepted Answer

Separate the file size from the size of the decoded image in memory, and use appropriate caching and resizing for display instead of loading a huge asset for every device.