Assuming you've default installed everything, in My Documents will be a SH3 folder. Open the folder inside there called data, then the folder called cfg inside that one.
(C:\Documents and Settings\Albert Hess\My Documents\SH3\data\cfg)
Open the file main.cfg with NOtepad, or other editor. Look for [TIME COMPRESSION] You should see this (although your settings might be different than mine):
[TIME COMPRESSION]
TimeStop=0
RealTime=1
LandProximity=32
CriticalDamage=1
CrewEfficiency=1
AirEnemyDetected=1
SoundEffects=2
CharacterAnim=4
EnemyDetected=1
RadioReport=1
Particles=8
PrayState=8
HunterState=32
3DRender=128
Maximum=1024
Set maximum to 2048 or 4096 if you want to go faster.
As long as we're here

here are several other settings you might consider changing:
LandProximity: I have mine set at 32, as I got tired of the extremely low default setting. 32 is fast enough to satisfy me when navigating close to shore, but is also slow enough that I have time to go to TC1 if I've mis-navigated and are about to run aground.
EnemyDetected & AirEnemyDetected: I have mine set to 1; better safe than sorry!