I had a lot of frame jumps in almost every moment, including the loading pages with the models moving.It was a problem that wasnt solved changing the specs to "low grafics", it was hte same in high, medium...

I decided to install the catalyst drivers and this fixed the problem temporary but have to install iy every time i restart the computer beacuse if i dont do it the problem reapear.It seems to me so strange.

I hope this can be a fix for others.