Tempo change?

It seems to me that what I'm doing should be a fairly common task in Reaper. I could not for the life of me find it in the manual. That is not to say it isn't there but, the manual has you doing a dynamic slice move. I was trying to do a dynamic slice on all audio tracks and then insert a tempo change marker. Problem was all the slicing starting eating up my CPU. The method described above isn't as slick as PT but it is more than usable.