Bug 180929 – REGRESSION (r225789): 35% regression in cold time-to-first-load by enabling service workers

• Status: NEW
• Component: WebKit2

[Tim Horton]

Created attachment 329646 [details]
test app

Steps to Reproduce:

1. Run the attached test app.
2. Revert r225789.
3. Run the attached test app again.

Expected: Relatively similar results.
Actual: GlobalCold Navigation Time goes up by 35% (for me, ~330ms -> ~450ms)

This measures the time it takes to load about:blank in the first WKWebView in a given UI Process. Other metrics (subsequent views, etc.) don't similarly go up, so this has to be a fixed one-time cost of some sort. I haven't looked at traces yet.

[Tim Horton]

> Other metrics (subsequent views, etc.) don't similarly go up, so this has to be a fixed one-time cost of some sort.

Actually, not true, they just go up by much less (5-10%)

[Radar WebKit Bug Importer]

<rdar://problem/36111525>

[Chris Dumez]

Could be due to the fact that we have to wait for the SW database to be read from disk before we can serve the first load.

[Chris Dumez]

(In reply to Chris Dumez from comment #3)
> Could be due to the fact that we have to wait for the SW database to be read
> from disk before we can serve the first load.

(and reading the SW database also requires the StorageProcess to be launched.

[youenn fablet]

We can probably easily optimize the case of non HTTP/HTTPS main pages.
We know about:blank will never get intercepted.

[youenn fablet]

(In reply to youenn fablet from comment #5)
> We can probably easily optimize the case of non HTTP/HTTPS main pages.
> We know about:blank will never get intercepted.

Filed https://bugs.webkit.org/show_bug.cgi?id=180976 for that purpose.