hello, yes you're right - that's unusual, the portable firefox versions should be more in the range of 70MB. can you use a tool like www.jgoodies.com/freeware/jdiskreport/ to inspect what exactly is taking up the space and report back here in the forum? thank you

Hi, here are screenshot of result:

http://oi40.tinypic.com/rarnf8.jpg

http://oi41.tinypic.com/2z3qgrp.jpg

when I check all firefox folder, only one file has 20MB, it is xul.dll, and several files have 2-5MB (D3Dcompiler, omni.ja, mozglue.dll, gkmedias.dll), so, I don' see any reason for 650MB.

you might want to move further down the folder tree on the left to see in which sub-folder these amounts of data have amassed...

Data ---> Profile (605MB) ---> IndexedDB (582MB) ---> there is written https+++mega.co.nz

and inside of this folder is idb folder with many folders and files. should I delete it? mega.co.nz is extension for that website (it is for storage of files) and maybe they downloaded automatically some sqlite files.

OK, just to say, I deleted all this folders inside of idb and everything is OK now, when I login to mega there is no problem and firefox is now 80MB :)

thank you very much, for me, problem is solved.

ok, in case it reappears in the future you should also be able to clear this database from Firefox/Tools > Options > Advanced > Network > Offline Web Content and User Data.