931959 - (Frame-Rate-Drop-JS) Frame Rate Drop Root Cause: JS

Status: RESOLVED WONTFIX

(DevTools :: Performance Tools (Profiler/Timeline), defect)

Description

[Axel Kratel]

As a web app developer, I would like to be able to identify JS code that causes frame rates to drop.

Acceptance Criteria:
* find in the recording where JS engine was linked to a frame rate slowdown
* find int eh recording places where the browser spent a lot of time in the JS engine
* Be able to drill down to see the actual JS function or line of code that was associated with the slowdown
* Be able to distinguish from external slow down causes versus problems my own app is causing. In other words the recording should be tab specific or app specific (FxOS).

Note: there are several scenarios that JS can cause slowdowns, we may want to break up this user story into the scenarios. For example:
* TIme spent in JS engine is short, but subsequent graphics consumption is high
* Time spent in JS engine is long, not necessarily associated with high graphics consumption.

Visualization could be done via time-based flame chart where every frame is broken down into where the browser spends time.

Comment 1

[Greg Tatum [:gregtatum]]

I believe this is no longer relevant.