Open Bug 1421074 Opened 2 years ago Updated 1 year ago

Loading DevTools on a disk-bound machine is slow with MOZ_Z_inflate_fast

Categories

(DevTools :: Framework, defect, P3)

defect

Tracking

(Not tracked)

People

(Reporter: gregtatum, Unassigned)

References

(Blocks 1 open bug)

Details

Loading DevTools on a disk-bound machine is slow, most of the time is spent in "MOZ_Z_inflate_fast". I tested this on my older Windows 7 machine.

This is a recording of DevTools startup, an filters on "MOZ_Z_inflate_fast":

https://perfht.ml/2hXnlSA
Hum. Hard to say if it is really slow or if that's just because we are loading way too many JS files/bytes?

All this comes from module loading. Either JSM or our custom loader.
Both codepaths ends up loading JS files in/from the startup cache.
This is also used by Firefox UI. I would expect that to be decently fast.

It may be interesting to see how different is the profile if you pass "-purgecaches" to firefox
It should disable this cache and reload files from omni.jar. It should be significantly slower as I believe we store a bytecode or at least some already parsed data into the startup cache.
I will try and do another run next time I'm sitting at that computer.
Priority: -- → P3
Product: Firefox → DevTools
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