SNES wins by a landslide against the NES, and then the Wii, Gamecube, and the worst of them all, the N64.
The SNES really was plagued with a turtlish CPU. It's an interesting chip, although pretty stock. I wonder why they opted for such a low-power CPU yet had a special sound chip made specifically for the console. Oh wait...that's right...because the CPU would already be so busy with number-crunching that handling music and sound too would have been more than it could cope with for complex programs. The fastest SNES game I've seen is Uniracers...sure, it zips along, but look at the simplistic graphics. Designers HAD to cut corners just to get decent performance. And it's not like stock 65816's didn't come faster...they just didn't opt to use said faster chips (probably financial reasons behind this). This lack of CPU power created a "tolerance" for slowdown.
I once spoke with someone who claimed that they were able to increase the performance of the SNES by tweaking the clock chip. I don't know if this was true or not. However, back in the NES days, a friend of mine and I removed the 6502 from an NES machine and inserted a 4MHz 65C02. A lot of games wouldn't run, but a couple did. They were quite unplayable though...it seems that the interface chip is governed by the CPU and operates too fast if the CPU speed is increased. So the controls worked too fast for the games, events were skipped left and right.
