Generally, non-compete clauses can be enforced. I'd add to Curtis' comments that your fee is a factor as well in determining reasonability. If they paid you $5M not to perform for that period of time and your typical annual revenue is, say, $100K, a court might think such a clause very reasonable indeed.
Comments by the others on this thread seem on point. Frankly, unless the money was really good, I'd only agree to a very short (weeks?) post-performance non-compete period. To my mind, the question is one of advertising for that period, not actual performance. How can sales of tickets for the event you're doing be hurt if the prospective audience doesn't know you're going to perform again locally? Maybe, then, it's really a matter of promising that you won't advertise any upcoming performances until after you do that show.
One other thought: depending on what's in your act and how unique it is, you can ask the people who drafted this contract why others can perform the same tricks in the area but not you. The reasoning of a post-performance non-compete in this circumstance is that people would not go to this particular show of yours because they know they could go to another show the next week (this ties into my point about advertising) above). But if others in the area are doing "similar" acts (i.e., assuming you're not the "only game in town"), then in a way it kind of defeats the purpose of a non-compete, no?
Good luck with your negotiations.
P.S. Unless the venue is in a really rural area, the 100 mile radius clause seems outrageous.