New beautiful notebook....where is the problem? :(

[Sackboy]

This week end i tried dolphin on my girlfriend's new notebook:

Processore Intel® Core™ i5-450M
(2.40 GHz, fino a 2,66 GHz con Turbo
Boost Intel®, 3 MB Intel® Smart Cache).
RAM 4 GB. Hard Disk 320 GB.
Scheda grafica ATI Mobility Radeon
HD 5470 da 512 MB dedicata. DVD SM.

The games that i tested were NSMBW and Mario Kart..At 800x600 dolphin can runs at 60 fps,amazing emulation of real console,but on full screen at 1366x766 (something like that...) the situation fall down and it appears like a slowmotion movie! Where is the problem..is the videocard or else?