The hacker's jump is feeble

64-bit Linux build.
The hacker is not able to jump very high. He may be a bit of a couch potato, but he was a good deal more agile in the DOS version. This is very noticeable in the low-gravity area on the reactor level; try as I might I cannot make the jump to get to the second chamber and pick up the flechette.

I think this may be a timing issue with the physics. From my reading of the excellently commented, very clear and thoroughly readable physics code, when the hacker jumps he is pushing off the floor and will immediately leave it. A jump should really be treated as an impulse which imparts a fixed velocity regardless of the integration time, but it is instead treated as a continuous force over, effectively, a single integration period. So the faster the physics clocks, the feebler the jump.