276925 - high (100%) CPU usage while loading page into a tab

Status: RESOLVED DUPLICATE of bug 269767

(Firefox :: Tabbed Browser, defect)

Description

[Valdis Kletnieks]

(reproduced with last night's build: Mozilla/5.0 (X11; U; Linux i686; en-US;
rv:1.8a6) Gecko/20050103 Firefox/1.0+)

If running with more than 1 tab active, the CPU usage climbs to 100% while a
page is loading into the currently selected tab.  CPU usage is normal (5-10%)
if only one tab is open, or if you click on another tab that contains an
already loaded page. Clicking back and forth between the loaded tab and the
loading tab will generate 100% spikes when looking at the loading tab, and
dips when looking at the loaded tab.

To reproduce:  (it's more obvious on a dialup or other slow access)

0) start a CPU monitor such as gkrellm or similar
1) visit any page at all, and let it finish loading
2) control-t to open a new tab.
3) visit another page in the new tab (preferably a slow-to-load page to
make the effect more noticable).
4) Watch the CPU usage climb until that tab finishes loading.
5) clicking the tab from page (1) will drop the CPU usage, and clicking back
to page (3) will again peg the meter if the page is still loading.

Sorry, I don't have a build created with -pg for profiling, or I'd tell you
where the time was going....

Comment 1

[Ryuichi KUBUKI]

*** This bug has been marked as a duplicate of 269767 ***