Speed is an individual stat, initially equal for all troopers. It essentially represents your Trooper's movement speed. Snipers or support roles shouldn't worry much about this stat, but assault troopers rely on it pretty much.
Ways to Alter Speed
- Manning a Helicopter (significant boost).
- Utilising Wife Beater (+30%).
- Utilising Thermos of Coffee (+25%).
- Upgrading to Amphetamine Shot (+100% for 500 turns).
- Upgrading to Hurry (+10%).
- Upgrading to Hyperactive (+50%).
- Upgrading to Sprinter (+100%).
- Upgrading to Survival Instinct (+50% under 50% Life Points).
- Upgrading to Enthusiastic (+25% on 100% Life Points).
- Upgrading to Huge Calves (+25%).
- Upgrading to Sturdy (negates heavy weapon penalty).
- Carrying heavy weapons (effect stacks).
- Utilising Heavy Armor (-20%).
- Upgrading to Heavyweight (-20%).
As you can see, there's no direct way to hamper the enemy's speed.