The speed loss isn't just the video speed, but shared memory video also extracts a toll on the CPU as the CPU can't access the system RAM while the video chip is reading it.
You'll find that many games will list a 3D video card. If so, you shouldn't try this on a shared memory video system.
Bob
I was just wondering how powerful the Ati radeon IGP 345M is (64mb upto 128mb shared). I know its not great for games but what level of games can it handle? (i mean playable i dont mind about all graphical option turned off and in low res)
i know that other specifications effect laptop speed but assuming that everything else is upto scratch what can it do?
Thanks

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic