latest version hangs every 10 seconds

Seems quite a few people experienced difficulties with the latest FF update. Me too. It was the FEBE extension that actually spared me of having to make a completely new FFP (=Firefox Portable).

That's what I'd do with my simply working mind: install Chuck Baker's FEBE extension in your present, hanging FFP (FEBE needs JavaScript enabled). Back up the *entire* profile with FEBE. "Install" the latest FFP completely anew in a new folder. Install the FEBE extension in that latest FFP. And, at last, make FEBE restore the previous profile in the new FFP. No garanties for anything! Perhaps make a 1 to 1 backup copy of the first FFP folder. I'd do everything on the HDD for speed reasons and then copy the finished product over to the USB stick.

http://customsoftwareconsult.com/extensions/febe/febe.html

You have something that is writing to your flash drive every 10 seconds. When writing to flash, Firefox can't read. Since the whole app is ON the flash drive (all DLLs etc), it will hang while writing. So, you need to minimize writes as much as possible. Most likely, you're using an extension that does something with sessions (saving a session, restoring a session when you restart, etc... NONE are recommded within Firefox Portable). Not sure why, but the behavior of these changes as FF is upgraded sometimes.

First, try disabling all your extensions and turning off history, cookies, etc. See if it works ok. If it does, enable things one at a time to find the cuplrit.