Very poor gaming experience. HELP!!!

[RonnieNine]

Sometimes games like bf3 are running smooth on ultra settings (SP) but if i join a server it lags even on medium.Why? FarCry 3 Lags on high settings too, but sometimes not.What i have to do to upgrade gaming power?
BTW i have the next PC:
ASUS K55DR Notebook
with
AMD A8-4500m (Quad-core) (i am satisfied with this one)
AMD Radeon HD7640g+7470M 1gb (Dedicated 1.5 gb) (this is the problem? how should i fix it?)
4GB DDR3 (Or this?)
Please help me!

 

[commando carrotz]

bf3 probably lags when you join a server because of your internet connection, but another thing could be your graphics card to run such demanding games on your graphics card won't give the best results, is this a desktop or a pc? btw your ram shouldn't affect your gaming performance by a lot

 

[RonnieNine]

Its a notebook btw. AND YES! my internet connection its a disaster even on my pc w\ cable (yes im using Wifi :\ )