maybe Jim's situation is the odd one: I have noticed that the RF version of any remote is a bit slower than the IR when a remote can be run either way. The worst situation that I had, though, with the slowest response, had RF interference from an alarm system in the area of the receiver. Is there any way you could relocate the receiver for a test?
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw