That depends on how much video RAM the game wants to use. A game with a lot of textures (like most modern titles, really) would run faster with more video memory, as it wouldn't have to swap textures in and out of its allocated area. This would be helpful in first-person perspective games where a snap turn could bring surfaces into view that weren't previously visible and thus needs to be swapped, leading to jerky frame updates...
Also, faster RAM would mean better performance for the Intel HD 3000 GPU, and 1600MHz RAM today is not expensive.