I use a branch for netplay that allows us to use Dualcore. While Frameskip doesn't have as large of an effect, it's still a tangible 15 - 25% on computers when it's having trouble maintaining full speed.
The GPU thread is the main bottleneck in most games from what I've seen on IRC. By using Frameskip, you can lessen that bottleneck a bit. Does it mean it won't be the bottleneck? No. Does it mean that the CPU thread won't become the bottleneck very quickly? No. But in a lot of games turning on frameskip is a legitimate way to boost speed even on computers with really good graphics cards.
The GPU thread is the main bottleneck in most games from what I've seen on IRC. By using Frameskip, you can lessen that bottleneck a bit. Does it mean it won't be the bottleneck? No. Does it mean that the CPU thread won't become the bottleneck very quickly? No. But in a lot of games turning on frameskip is a legitimate way to boost speed even on computers with really good graphics cards.