Good radio wireless remotes, like PocketWizards, fire extremely fast, well within the time the shutter opens; I pushed mine a long ways past 1/1000 before I saw problems with a black bar beginning to creep into the image.

I think they're both adequate for normal situations. It's when you get into adverse situations that you'll see one work better than the other.

If you're in an area with a lot of radio/electromagnetic noise or need to shoot through a metal mesh fence an optical trigger will probably blow away the radio trigger.

If you're not line of sight, or dealing with dust, rain, snow or fog or at a distance that the optical can't cover, then radio triggers will win.

I have PocketWizard remote triggers because I needed something to work in really lousy conditions outdoors. I've used them in the rain, dust, heat, cold, up in grandstands, running all over the place, without needing to worry whether I was where the trigger could see me.

I think reliable triggering for your shooting conditions is the most important thing, over speed or whether it's radio or optical.