This should be a nice simple open-and-shut case: Why does Sonar 7 sometimes slow down during track creation or playback? It may look like a gray mass of text below, but am only trying to give the clearest possible picture at the outset. THANK YOU IN ADVANCE for any advice you can give!
There are two clear-cut ways this problems happens -- when it does:
1. I'm adding layers upon layers (that's what I call 'em) in a track, rarely more than 3 total, as always with a lot of deleting and redoing. The background field clouds up (as it's supposed to) showing where starts and stops have lain. (Or just the starts?) The drag is worst when I finish one complete element of the track (e.g the right hand part or a solo line in the top voice) and then add others under it.
1a. If I lay one complete track and commence adding a separate/parallel one (e.g. in the default "MIDI 2"

it
really starts lagging.
2. I'm on an instrument other than the one I normally create on (Rodgers church organ) -- basically a Casio WK-1500 or 35-year-old Clavinova. Can spend a whole hour (or say 10 minutes) running my tracks just fine on these and then a brisk one will move at a crawling pace -- even seems to resist speeding up with the little inline BPM box!
Does a track that slowed down in the creation phase run OK if I close everything and run it another day? You would ask me that -- believe it does, and that the tracks that lag on "other" instruments do fine once back on their "original" one.* Can check that if need be -- church is 30 miles from home and puter, alas.
I attempted a google on this situation. If I understand latency correctly, that is not the problem. The tempo of the music I've already sequenced and am hearing as I add to it gets slower, the track on the screen too accordingly.
*Have never finished a dual-track project because of this problem. Really want to -- triples, too.