DP SV SLOWMO

From Quake Wiki

Cvars:

"slowmo" (0+, default 1)

Sets the time scale of the server, mainly intended for use in singleplayer by the player, however potentially useful for mods, so here's an extension for it.

Range is 0 to infinite, recommended values to try are 0.1 (very slow, 10% speed), 1 (normal speed), 5 (500% speed).