The run
race_ovalrace: Red Dragon 0:05.6
is not the best you can do with old physics. I did 4.8 some time ago, but it was done locally.
I also tried teachers with old physics and got 32.x with little effort (5-10 tries).
These times fit into div's statistic. (sorry for showing-off

The new physics are indeed slower, which is really annoying (for me) on large maps.
On the contrary, they feel better on small maps and some trickjumps became surprisingly easy. Thus I think 1on1 gameplay will be better while ctf/race gets slightly worse.
EDIT: about the "impossible" jump on test99. Is that the one over the slime? For me its possible... but the rocketboosting is impossible for me.