1308326 - Huge startup perf regression with Test Pilot + Tab Center + Activity Stream

Status: NEW

(Firefox :: General, defect)

Description

[Markus Stange [:mstange]]

On a fresh profile, Firefox takes about 3 seconds to launch and show about:home on my machine. After installing Test Pilot and enabling the addons "Tab Center" and "Activity Stream", it takes about 10 to 12 seconds.

Here's a profile from Dan Callahan's machine:
https://cleopatra.io/#report=07b15e5c88a431b4fa5e41982caeb4c92003cae1

There's a lot going on in that profile, but not much is actually happening. I challenge everybody to find a single sample on the main thread where we're doing actual work, and aren't just stuck in some kind of overhead.

For example, the add-on SDK's module system seems to have a huge amount of overhead - we're evaluating included JS files again and again, and are spending huge amounts of time in readURI (which only checks URIs and constructs channels, but doesn't actually read the file).

Comment 1

[Paul Oiegas [:poiegas], PM for (Ecosystem QA, Services QA, WebCompat QA, Hubs QA teams)]

A discussion thread was already started a few days ago on GitHub for Activity Stream performance issues that might be related. 
https://github.com/mozilla/activity-stream/issues/1420