Something scary just happened outside the gate to Lut Gholein. My paladin (a HC SP cleric) and his mercenary couldn't kill the beetles quickly enough, so in order to manage the battle I started converting them. It seemed to work fine, but then suddenly the frame rate dropped to 'incredibly choppy', and my barbarian mercenary screamed and fell down dead. It sounded as if a lot of lightning was being discharged, but I couldn't figure out how that could have happened. I thought it was some kind of freak occurrence, and figured that I'd be safe as long as I'm not the one surrounded by beetles. But then it happened again a while later, and my paladin took some heavy damage. I desperately chugged a full rejuv and then saved and exited the game. By that time the screen was basically frozen.
Thinking back, I now wonder if the discharged lightning from an enemy beetle can make a converted beetle discharge its lightning, which then makes the enemy beetles discharge their lightning, thereby creating a loop of lightning discharges which is potentially lethal to anyone who isn't immune to lightning. And with more than two beetles the number of lightning bolts would grow exponentially, which would indeed freeze the screen rather quickly. That's my best guess, but when I searched for discussions of this phenomenon I came up empty. I won't be converting any more beetles though.
Hmm, lightning ping-pong, sounds interesting . In normal and nightmare, they might annihilate each other, but the ones in hell mode are immune to lightning. Player characters and mercs aren't, however.
I ask myself what happens to packs of dolls or suicide minions if half of them are converted. Maybe a chain reaction and instant death to anybody in the vicinity? Mercs are immune to the explosion, however.
Hmm, I think I saw something like this in Tal Rasha's tombs. At least I got the 'increadibly choppy, almost to a halt' thing happen. The place got quite dark, too (I think the game tried to minimize processor-demanding light effects?). The game moved only a few frames along every 10-15 seconds or so. I was about to S&E (managed to get the Esc screen up - had to wait 20 seconds for it to appear...) when I changed my mind and cast TP and got out instead. Click and long wait after every action...
While I was in town, the game soon got back to normal.