As per title:
AI divers, once in "combat" behaviour move very slowly and often move in a circuitous route to get to their waypoint if they are swimming.
They are fine in "aware", "careless", and "safe".
Similar problems occur if they are in "stealth".
If you give them a waypoint using "safe" or "aware", they are fine up until an enemy is detected, and then they slow right down.
{F22752}
Download and install attached mission.
Once mission is running, go to the map screen
Then accelerate time if you like.
Watch the two groups try and get to their waypoints. The dots are placed every 5 seconds.
Green dots = leader position for group in "aware"
Red dots = leaders position for group in "combat".
You should see the green dots reach their destination in good time, whereas the other group flounders around and often climbs up on the shore.