Minecraft crashing

I've been having a lot of issues lately with my performance on my machine and on minecraft, averaging below 20 fps even when it's 1/4 the size of my screen. I have an antivirus installed by my organization "Sophos" that uses up memory and CPU constantly but not so much that it would impact minecraft to this level. I also have the issue for a long time that my game would suddenly not working, it would freeze with the not responding message at the top and turn white, next thing I know I'm in the disconnect lobby of whatever server I'm playing in. I'm not sure if both of these are correlated but I think my minecraft just gave out today.

MultiMC version: 0.7.0-3863Launched instance in online modeauthserver. - Pastebin.com