fastest will be a vanilla rom with jit installed. check out grdlock's vanilladroid+jit, all found on his site. i am using aloyious v6+my addons and is very stable and fast. has a lot of features that no other rom has since it was ported from the hero, like open market and has better cell service as well. i am actually basing my rom that i will create after vaca on this port, unless something better comes out when i am gone.
i recommend testing all the ones you think look nice. i have nand more times that i can count. i think i once flash 9 times in a day testing diff roms for features, crashes, etc. one user may have an issue and you may not. worst thing that can happen is you have to go back to a nand backup. you end up learning a lot when you do this.