I think number crunchers here before have done so already, and found the PCE Hu cpu to be faster over all then the Snes cpu. Regardless of that even, the proof is in the games, where as you do see the PCE move alot of sprites alot faster over all in everything, and you hardly ever have any real slowdown on the PCE versus the Snes on comparable titles like Gradius 2 PCE versus Gradius 3 Snes, or Rayxanber 3 versus Super R-type on Snes.
Game makers them selves from most companies complained that the Snes cpu was just a tad too slow at times and far less efficient for their liking compared to TG/PCE and Genesis cpus. It took them quite awhile to really get a grip and overcome alot of the slow down probs in the games Snes wise, and they never did fully, no matter what trickery they tried to use. My meager opinion on it is Nintendo was too interested in the graphics chips and sound chips in development, and in the design room at the time, 88-89,the hardware guys and Nintendo programmers just didn't realize that games were going to be as in depth as they were getting upon the Snes release.
Snes release titles are a prime example of this mentality, Super Mario World, F-Zero, and Pilot wings, all nice looking, but basic in premise, with Mario having the most going on on-screen. Once the complex games hit, like Super R-Type, Final Fight, Super Ghouls and Ghost, Gradius 3, Contra 3, ect.. it became painfully obvious that the Snes CPU was having a hard time coping with on screen action that really required faster cpu work in order to eliminate slow down. They prob felt worse comes to worse, they could offload alot of the work onto the graphics chip. Turns out if that was the case, it was a poor decision. The Snes still did really amazing things though when people learned to optimize its cpu, graphics and sound ability.