Intrusion Detection slow speeds after a few minutes

[notrox]

I'm having an issue when I enable Intrusion Detection with IPS mode (all hardware offloading is disabled) enabled. I get full gigabit line speed then after a few minutes, speed drops down to 120-130~ megabits. Restarting the service allows me to download at full speed then the speed drops back down as before.

I've tried all Pattern matching options without any change. Not sure what else to try.