Yeah, time can be a drag. In the jam last night, the trombone player and I discussed whether there was a magnetic anomaly under the floor of the joint that always drags the tempo of a swing tune down to about 140 bpm. Doesn't matter where it's counted off, that's what it will get to in the first couple of choruses. This is with the sitting in bassists and drummers of course...
I actually tried in one tune to get the drummer to start pushing (he was the one most affected by the tendency to drag), so I turned toward him and played simple rhythms for 8 bars, rushing, to try to get him to speed up, but it didn't work. Oh well....