Learn English – “…programs that each perform…” vs “…programs that each performs…”: which is correct

My opinion: plural except in a special case (see below). The only explicit statements I've found to corroborate my opinion are on Answers.com regarding subject/verb agreement and a chat board for college students, neither of which strikes me as particularly authoritative. Nothing I can find indicates that anything other than a plural is appropriate when the subject of the sentence is two of anything conjoined by "and," including two gerunds.

Special case: gerunds that go together to form a unit of activity: drinking and driving, or texting and driving, etc. In those cases, when the point is the combined act, then a singular is nearly always used. Now that I think about it, the singular or plural helps differentiate: "walking and chewing gum is a skill mastered by most people" versus "walking and chewing gum are physically active tasks, thinking is not, but all three burn calories."

If you are referring to multiple blue doors, multiple yellow doors, etc, then you say "doors" but if you say, if you choose the red, yellow, or blue door, then you win a prize. (in this case the word OR clarifies that the descriptors are for a singular noun.)

There can be multiple choices, but the noun describes the number of things of that choice. If there is only one of each, then the noun is singular.

You can also say, operate either the On switch, or the Activate Switch, and the machine will run smoothly.(This sentence is specifying a choice of one or the other.)

Or you can say, Flip the On AND the Activate switches to start the machine. (this sentence is referring to turning on both switches at the same time, so the noun is plural. I hope this helps.)