when firefox first loads why

Can you elaborate more concisely what you are asking? Maybe what you are seeing is some elements of the page loaded but other elements still rendering.

ok! when i click on the firefox icon it open firefox in about 2 seconds the pointer changes to the little round dial to show it is working and will be working for 10-15 seconds. but if i click open firefox click one of my bookmarks it will go strait to it and the dial will still will still run for the 10-15 seconds. the only add on i have is fasterfox. i have firefox set to clear cookies and caches when i close firefox. in 9.04 with firefox 3.0 it did not do this ,but with 9.10 with 3.5 it does .i run 10gb internet access through a router. at audit my pc test run 10.19 mbps download and up loads of 858.5 kbps . so i would like to know what firefox is doing in that 10-15 seconds it is running at start up. tracker cookies, writting a start up or history log .

try to set your home page to a blank page and see if the "problem" persist.
desactivate the addon and/or the option of clearing the cache to see where the problem come from (if there is any).

tried a blank page still does it, restarted disable add ons ,restarted allowed cache restarted ; and still does it .. ?? could it that my access is fast enough that firefox has to catch up with it .?? i do have swapiness enabled and ppa.launchpad.net could they be a factor here ?

Thanks Vikram, that solved my question.