318378 - tab switching extremly slow / thumbnail preview on tabs extremly inefficient

Status: RESOLVED INCOMPLETE

(Firefox :: Tabbed Browser, defect)

Description

[Kuno Meyer]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8) Gecko/20051111 Firefox/1.5
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8) Gecko/20051111 Firefox/1.5

tab switching is extremly slow if you have many images open. "images open" means an image (in contrary to a HTML page) as content. Tabs have to be created by a mouse "middle click"; opening the images from the URL bar does not work.

Reproducible: Always

Steps to Reproduce:
http://www.arttech.ch/Webcam/mobotix.jpg

1. Open the above link with "middle click" on 15+/20+/25+ tabs (depends on machine speed) inside the same browser window
2. Try to switch between the tabs (Ctrl-PgDn/-PgUp)

Actual Results:  
The tab switch is extremly slow, with a delay of 2-5 seconds (depends on number of opened tabs and machine speed)

Expected Results:  
Reasonably fast tab switch, as experienced on Firefox 1.0.x. (<0.5s)

Comment 1

[Kuno Meyer]

Ok, first correction: The point with "middle click" does not apply. It happens also if you open the tabs from the URL-bar with "Alt-Enter".

Comment 2

[:Gavin Sharp [email: [e-mail]]]

Just to be clear, by "thumbnail preview" you meant the small 16x16px icons in the tab itself (from bug 125998)? There are extensions that display larger thumbnails, if you're running one of those then slowness is expected.

Otherwise, see bug 304561.. basically looks like you're using images just under the limit imposed by the fix for that bug (images with either dimension greater than 1024), and using many of them. You could try setting the pref (browser.chrome.image_icons.max_size) to a smaller number (or 0) to disable those previews and see if that solves the problem.

Comment 3

[Kuno Meyer]

Yes, I do mean the 16x16px icons from bug 125998, and ...
Yes, setting (browser.chrome.image_icons.max_size)=0 does solve the problem.

So this bug here could be a dupe of bug 304561, but my the delivered link does present only a 640x480px image, and having 4 of them open does already raise the pane-switch time to ~1 second. (my test machine here: a quite old AMD running at 1.4GHz with 256MB Ram, Windows 2000.) 

Pointing out, that (browser.chrome.image_icons.max_size)==1024 is a bit too optimistic for low-power machines.

More probably, this bug is a "depends on 305986", because we need a way to _cache_ the 16x16px thumbnail?

Comment 4

[Sindiso]

Tab switching is very slow indeed!

Comment 5

[tech]

with linux releases of mozilla-suite seamonkey and firefox tab switching is extremly slow all the time, even if there are no pictures on the pages

Comment 6

[Steve England [:stevee]]

Reporter, do you still see this problem with the latest Firefox 2? If not, can you please close this bug as WORKSFORME. Thanks!

Comment 7

[Kuno Meyer]

Sorry, but still the same behaviour in FF 2.0.0.4. With just seven open tabs displaying the image at the reported URL, tab switch (or even tab pane redraw) requires significantly more than 0.5s, perhaps 1s [measured on an old 1.6GHz Athlon].

I still have the same opinion as in comment #3.

Comment 8

[Martin Stubenschrott]

With my self written add-on "Vimperator" i can measure the time for switching 5 tabs (with  :5time :norm gt)

Results:

a) Menubar, all toolbars hidden, tabbar hidden:
-> average time: 35ms

b) Menubar visible, all others still hidden:
-> average time: 40ms

c) Menubar and Location bar visible, tabbar hidden
-> average time: 65ms

d) menubar, locationbar and tabbar visible:
-> average time: 90ms

All numbers were taken on FF3, alpha9pre

I might file another bug report for this when needed as also the location bar slows down tab switching considerably, which just shouldn't be so much.

Comment 9

[Martin Stubenschrott]

Sorry, forgot to say, i am on Linux, with the default firefox AND gtk+ theme and i could hide the tabbar even when >1 tabs are open with :set showtabline=0 in my extension

Comment 10

[Daryle Tilroe]

Just another data point.  I tracked my slow tab switching to primarily this icon preview issue.  I upgraded from MOZ 1.7.2 to FF 3 and all of a sudden a set of tabs that I often had open was painfully slow to switch around in.  They were 10 pages that mostly had images up to 1024 x 1024.  Disabling the tab icons (browser.chrome.image_icons.max_size=0) mostly did the trick to bring the switching back to the near instantaneous response in 1.7.2.  The two largest ones, 1024 x 1024 are still slower to switch to, almost a second to redisplay.  I'm not sure I see any bugs for this last problem.  There is one for larger images but it refers to the image getting compressed in memory.

Comment 11

[Daryle Tilroe]

The above secondary bug I was referring to seems to be more about the image being "paged out":  https://bugzilla.mozilla.org/show_bug.cgi?id=430106

As I mention in my comment there:  there is something less efficient about how the image gets rendered in FF as opposed to the old 1.7.2 code.  It is really interesting to see the effect of dragging a window across the old and new browsers both displaying the same image.

Comment 12

[Daryle Tilroe]

Aha.  I found the problem.  It is with the scaling.  With 1.7.2 a scaled image had almost no performance hit and was better rendered somehow.  With either it appears that, if the image is scaled, every time it (or part of it) is redisplayed it has to rescale the whole thing; however FF 3 is much less efficient.  A simple test is to have two FF 3 windows open, side by side, of the same largish image, one scaled, one not.  Just drag some other arbitrary window over the top of one and the other and observe.  For comparison the same test in 1.7.2 does shows a *much less* noticeable difference.

This may actually be more closely related to this bug than it initally appears since both problems seem to highlight some inefficiency introduced in the FF scaling algroriths, in one case it is images on the page and in the other for the preview icons.

Comment 13

[Tyler Downer [He/Him]]

This bug was reported on Firefox 2.x or older, which is no longer supported and will not be receiving any more updates. I strongly suggest that you update to Firefox 3.6.3 or later, update your plugins (flash, adobe, etc.), and retest in a new profile. If you still see the issue with the updated Firefox, please post here. Otherwise, please close as RESOLVED > WORKSFORME
http://www.mozilla.com
http://support.mozilla.com/kb/Managing+profiles
http://support.mozilla.com/kb/Safe+mode

Comment 14

[Tyler Downer [He/Him]]

No reply, INCOMPLETE. Please retest with Firefox 3.6.x or later and a new profile (http://support.mozilla.com/kb/Managing+profiles). If you continue to see this issue with the newest firefox and a new profile, then please comment on this bug.