Snappy, January 19: Brought you by Ironic JS
January 20th, 2012 by tglek
Network Cache Horrors
Last week we discovered that our cache uses main thread locks to successfully block on off-main thread io. See (Bug 695399, Bug 717761). QA did an experiment which confirmed that our disk cache is performing poorly.
Flash Lag
We are looking into reports of flash lag, tracking Bug 720000. Initial QA data shows a significant slowdown when page is first loaded and smaller slowdowns later. There are also long browser pauses when the flash container progress freezes.
Profiling
Vlad continued work on non-destructive chromehang, Bug 712109. Client-side is ready to land and he is wrapping up symbolification for the server-side.
Interactivity profiler is now able to collect stacks on 64-bit MacOS. Benoit is looking for contributors to add Windows, Linux support (Bug 719536). I highly encourage adventurous contributors to help out with that as it involves modifying some concise, straightforward, yet highly ironic JavaScript. We are also looking for help with the profiler UI. If you are a skilled addon/frontend person, see Bug 719530.
Jeff posted an early preview of about:jank addon. He also working on measuring painting speed via telemetry. Note this addon is buggy and requires a very recent nightly.
Last week I asked for some laggy session restore profiles. I’m behind on reproducing those(will be done today or next week). I’ve been in email contact with several of the commenters. I really appreciate the data gathered so far.
Snappy UX
Jared landed smooth scrolling, Bug 198964. He is now working on hooking it up to scrolling via scrollbar, Bug 710373. Up next: fixing fallout from turning on smooth scrolling, hooking it up to the refresh driver and tweaking scrolling physics.
Marco landed inline autocomplete, Bug 566489 and is now fixing fallout from that too.
4 Responses to “Snappy, January 19: Brought you by Ironic JS”
For what it’s worth, the by far biggest issue that I see is Flash responsiveness. The way I’ve reached this conclusion is that anytime I disable flash my browsing experience improves significantly.
Unfortunately this methodology doesn’t tell much about what aspect of flash is causing snappyness issues. Initialization, blocking js-to-flash function calls, painting, etc.
One thing that has come up in conversations between me and jst a couple of times is that flash always on initialization of each instance does a flash-to-js function call by loading the url “javascript:window.location.href” or something similar. They do this to figure out the security origin that the swf should run in.
We could probably save a bunch on the cross-process communication that happens during startup by special-casing this load to always return the origin url of the loading page, without crossing the process boundary. location.href can’t be overridden anyway in JS (exactly for the reason that flash uses it), so we always know what the correct answer is.
Flash is a cancer when it comes to Firefox. I run NoScript and block Flash and all other plugin content. This leaves Firefox at least usable (despite a plague of other performances issues like zombie compartments, etc).
However friends and family don’t use NoScript (and who can blame them, it’s quite a geek-level thing to run) and subscribe to the evil wave of ‘social’ junk pervading the interwebnets. This inevitably leads them to run junk like farmville and thus Flash. This tends to make Firefox perform like a old geriatric dog.
Plugins should be banned from browsers.
@pd
you’re everywhere…and wrong.
just adblock would remove flash except when needed and it’s not geeky to use. and zombie compartments is not a performance issue but a memory one.
And it’s not that slow, I have more a slower browser filled with webgl and web workers than flash…
@tara
keep up the good work, I hope you will do a good work with snappy as nethercote is doing for memshrink. Firefox is improving!
@pd
Essentially almost all issues with Adobe Flash are (c) Mozilla – blaming Adobe Flash (which improved dramatically ever since introduction of hardware video decoding) just makes you ignorant of Flash performance in rival browsers.
Because HTML5 does not rival Flash in vectorized gaming and Google-sponsored browsers do not support h264, Adobe Flash is a MUST for Internet gaming and video.
I noticed that it takes a lot longer for Firefox to repaint itself when maximized with flash content – it repaints itself much faster without it. Same exact issue when tab switching.
Sadly, Chrome is the poster child to follow here. It does not slow down with Flash Content. Tab switching and repainting on maximization are instant. It also does not suffer from Adobe Flash content jumping (painting itself during the wrong time – out of sync with the page) which by itself is a massive eye sore.