Why Wii games are lagging?

[Zangetsu276]

I Just get a GTX 760 yesterday and today I tried to run Sonic Colors on it,everything is the maximum native resolution,anti-aliasing and it lag so much that is unplayable,I have tried to decrease resolution to all types and no speedup,tried to decrease anti-aliasing to none and no speed-up and I remember I finished it with a GT 630 with 2x native with just a bit of lag,completely playable,why I have all this lag?
Also only Wii Games have lag except New Super Mario Bros.

My specs are:
GPU: GTX 760 Zotac Amp Edition 2GB
RAM: 8GB Corsair 1600Mhz
CPU: AMD FX 8350 4.2 Ghz