It is Firefox 43.0.1 not 43.01
US English release notes Firefox 43.0.1
Ah, MilesAhead beat me to it:
Just one item in 43.0.1 notes. To do with MS signing blah blah
(Edit: although some may prefer yadda yadda)
Heh heh. I don't remember such a small version number change. But since it is one fix that may be the reason. They might have waited for more stuff if it wasn't an MS compliance thing.
If I wasn't on a Laptop I might switch to SlimJet. I occasionally use SlimJet portable. But it seems to just pull down the battery enough even when plugged in that it sometimes kicks into charge mode. The transformer on this Toshiba runs hot so I try to avoid pulling current.
I just updated SlimJet 126.96.36.199 to 188.8.131.52 and extensions and the rest seem to be ok. I just extracted into the old folder. I still don't use chrome sync so it's a plus if the browser will update similar to FF.