I'm able to make that jump as a heavy, which I believe is the slowest class in DR.
im gonna assume you used the gru, which i think gives heavy 127ish% movespeed on these servers (assuming they give 50% movespeed still) + small extra jump height. that is literally faster than everything else.
E:Okay maybe they only make heavy run at medic speed, but that means he's faster than the majority of classes.