I think this has to do with how the central pane flows over the background image. Basically, mozilla-bin uses about 1% of CPU time, but X spends a lot of time (50%+) spinning its wheels. The window updates slugishly. Either Moz is using a very poor way of updating the page to my X server, or the X server has some kind of deep seated performance issue. I'm hoping the X11 expert for Moz will know what's wrong. If someone could reproduce the "jerky updates" on Win9x/NT by scrolling the page by mousewheel, I'd say this is a valid bug for all OSes. Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8+) Gecko/20020202
how do you mean >60% ? while scrolling or when the page is loaded? for me, on WinXP, latest build (2002020409) scrolling up and down constantly by mousewheel causes about 60% CPU (Thunderbird 1GHz) usage on mentioned URL, that's right. But it's also about 15% on this bugzilla page. and the other pages layout is simply more complex. When page is loaded and not scrolled we're about 0-1% as is usual. i made a test using IE6 scrolling up and down on the page you meant, and it's consuming about 50% CPU, so i think there is no 'bug' with mozilla. not even a big performance issue. if it's not eating up your performance, when you're NOT scrolling, i suggest marking this one INVALID.
It is very slow to scroll using XFree86 4.1 and mozilla 0.9.8. On my Duron 800 it's usable but not pleasent at all. If there is something to be done for performance in this case then I would be happy. I tried the page using IE 5.0 on my PII-400, and it shows no sign of slowing down IE uses like 70% CPU while scrolling and feels smooth. Moz 0.9.8 uses 100% CPU and is very bad scrolling (maybe not even 400% CPU is enough, is the feeling).
It's because of the fixed background. You can't just scroll the page, it has to be completely redrawn.
Can't we just invalidate the parts that are "changed" ? If a page has one central column and big margins on either side, can't we just not redraw the side margins? There must be some sort of algorithm for that kind of graphics work.
I don't know how it's implemented in mozilla, but if one renders the different layers separatly and use the XFree86 RENDER extension to compose the images that sounds like it can take away some of the slowness. But of course it will never be as fast as when you just scroll the existing image and just invalidates a small part of the screen as "normal" scrolling do. But this is probably something for future versions of mozilla. Since IE in windows is way faster then mozilla there are clearly room for improvments here, but some profiling is of course needed to really know what the slowest part is.
Confirming this. Scrolling the same page in Opera 6.2 Beta Linux never seems to use more than 45% of the cpu and doesn't feel nearly as slow as in moz. 20020421 Linux.
Status: UNCONFIRMED → NEW
Ever confirmed: true
WorksForMe using FizzillaCFM/2002071208. Scrolling the URL results in at most ~50% CPU usage by Mozilla.
I still see incredibly heavy CPU usage on Linux/X11 with 2002071304. Mozilla starts chewing between 10-20% CPU time, and X has a heart attack and takes everything it can grab (70-90%). It gets so bad that my CPU meter doesn't update, and when I stop scrolling the window, it keeps "ghost scrolling" as the input buffer replays all the queued input. Something in Mozilla doesn't handle the background image/layering optimally at all. Which I find surprising, singe things like the xv extentsion allow for lots of really neat acceleration.
How about we try XPApps for this to start with.
Assignee: asa → sgehani
Component: Browser-General → XP Apps
QA Contact: doron → paw
Status: NEW → RESOLVED
Last Resolved: 10 years ago
Resolution: --- → INVALID
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