When I first played I never had an issue. Lately when I attempt to play with 6 bots it starts out ok then will start to slow right down, to the point where I can't shoot. When this occurs the terminal outputs several lines of "Warning : Connection problem." This is annoying when I've hosted the game and playing against bots.
After playing your (great) game for a while, i had this issue too. The weapon system had been slowed down, but driving around was possible at perhaps 25-50% of normal speed. I often discovered two (or more) bots crashed in each other, not moving any more. Killing one (or with a bit luck both) of them resolved the issue.
In other situations, this behaviour seems to be related to self-healing bots. Killing the affected bot made the game running normal again.