+1 on this topic. I've been able to keep my slaves from being stressed from too much lust, but I haven't found a way to lose the "very horny" malus in combat.
Looking at the code, it looks like an orgasm reduces Sense by 300 (to roughly 700) and Lust by a quarter (to roughly 750 if capped). Maybe if you're doing many continuous actions, you're crossing those thresholds by so much that it ends up stuck in the high range?