Enemy AI for Stealth Game

So, I've started the workings for a stealth game in the style of Metal Gear Solid (Top Down Camera, enemies have cone of sight, alert phases, inventory selector, KO'ing enemies and dragging them away, etc). I've been able to get the engine to work well so far and I modeled the enemy cone of sight and chase systems after examples I found online, but I've been having lots of trouble getting the enemies to chase me during an "alert phase" properly. When one enemy sees me and triggers an alert, the other will run through the wall and I have yet to figure out how to give them good path finding AI. At an earlier point in development, I used the pathfinding object to help enemies find their way around, but it would cause my frame rate to drop if the player moved around too much during an alert. I'd just like some help with getting multiple enemies to give chase by finding paths to the player. Thank you!