playing Daytona USA 2 Power Edition on Beginner course, i don't get any slowdown (it's the only course like that, all others have some slowdowns at some points, probably those famous "hiccups").
And what's interesting is i don't have any expensive unlocked Core i7 with 4 physical cores and 4 virtual cores @ extremely overclocked speeds, and no overclocked Geforce GTX 590 or something of the like, i don't have super expensive RAM...here are key specs of my main PC:
CPU: Intel i5 750 2.66Ghz Quad-core CPU @ 2.73Ghz, LGA 1156
RAM: G.Skill F3-12800CL7D-4GBRM Ripjaws 8gb 7-8-7-24 (4 x 2gb DDR3-1600, 2x dual-channel RAM kit)
Video Card: eVGA GeForce GTX 560Ti Superclocked 1Gb GDDR5 256-bit (PCIe 2.0 16x)
Sound Card: Creative Sound Blaster X-Fi XtremeGamer
i want to point out that you generally don't need an extremely powerful computer for emulation...yes you need power still, but don't try to HyperBlast your CPU like a supersonic rocket like most peoples did for trying to get a fair framerate with a poorly-emulated MAME with Daytona USA 2...that's just lame.
Good emulation is the key. Just look at the Dolphin Emulator, well-done emulation and i'm able to run tons of game with it, in HD, with a stable framerate!
Bart is doing a good job with his Supermodel emulator, there are bugs to fix and stuff to improve, but so far it look extremely promising and you can already play games with a good framerate!