Lagging when I'm lookng round with the mouse

Recently I've noticed I got a problem during playing Minecraft nowdays. The problem is that when I move around with the mouse while playing my game it lags alot. If I just stand still and do nothing or walking a straight line no lags happens. Only when I move my mouse.

I've been in forums looking for solutions, tried few helpful mods for performance, lowered my graphics in game to minimun, updated java, cleaned my computer from trash and such, looked on options on my graphics and graphiccard and reinstalled the game and nothing works. A few said it could be because of a malware program too but I've looked up and I don't got any program by that name they mention (STIJ.EXE).

I've tried in creative, survival, online and singelplayer and it stills lags when I'm looking around. Also, the fps can go lower than the picture says too (around 5fps is the lowest)

It began in 1.6.2 and the problem got solved by rebooting my computer. Nowdays it doesn't work at all with it and got worse during 1.6.4.

Any ideas what I can do? Some says it could be because how good and bad the computer is but I havn't had any problem with Minecraft's graphics at all with my computer until now.