People get so convinced that they have to play, play, play... more notes, more notes, more notes...
The better way to handle all of this is to start leaving out stuff. Stop playing when you sing. Play between your vocal lines. You don't have to be playing all the time. To me the whole "play, play, play" thinking is sorta beginner-ish.
It comes from playing drums. When you start out, when you go fast you tense up. You wish you could play real fast. Then you realize that as the tempo increases, if you start leaving out things you can avoid all the tensing up. With that thinking you can play songs at 250 and it's no sweat. Just keep leaving out stuff as you go faster. Don't let your mind go into a panic. That's the problem.
Realize that it's ok, and even often desirable to stop playing.