Description of problem:

There seems to be a very pronounced pausing (of about 1 second) in the Firefox 9 GUI and it affects everything from typing in a text field to interacting with the tabs, etc.  

It is seems to be related to the sessionstore section of Firefox, since increasing the browser.sessionstore.interval delays the occurrence of pauses, while decreasing it makes them more common.

I do recognise that on first impression this is probably isn't a bug since there are numerous web articles that advise increasing this value to prevent jerkiness, but I want to stress that this wasn't that noticeable in Firefox 8 or prior versions. But it is very noticeable in version 9 (1 second long pauses).

Version-Release number of selected component (if applicable):

firefox-9.0.1-1.fc16.x86_64

How reproducible:

Always

Steps to Reproduce:
1. Open up Firefox and type or use the tab interface
  
Actual results:

The interface pauses every few seconds for about 1 second

Expected results:

The experience should be relatively smooth

Additional info: