My Firefox has been slowing down a lot lately, gobbling up over 1 GB of RAM for only 2-3 open tabs. This is pure disaster on the old hardware I have at work. Starting it with a completely clean profile returned it back to normal speed.
Of course, add-ons are a big part of the problem, and I will have to select carefully the ones I want to keep. But I suspect that it is also full of useless baggage multiplied by Firefox Sync. My bookmarks list has thousands of entries, and I need maybe 20 of them. The rest was restored after I deleted them on purpose on one computer, or even replicated for unknown reason (the replication of existing bookmarks mostly happens when I log on from a machine I haven't used in months). I suspect that other data managed by Sync has proliferated the same way, and is one of the factors which slow the browser down.
I want to go through everything Sync manages, and clean out the unneeded things. I also want to set the Sync direction on seldom-used Firefox installs to readonly, so I don't get ages old data restored. I logged on to the Firefox Sync web interface, but it only offered me to delete everything. I couldn't manage FF installs with access to my account, I couldn't see the data and selectively delete parts of it. Is there any other way to do it?
I don't want to delete the stuff from a single computer and hope that it will stay deleted, because this is obviously not working properly.