Disconnections/High Lag in Merciless

I've been playing PoE for some time now and I've discovered a strange trend that I don't quite understand.

Upon carrying a character to the final difficulty level, the rate of disconnections and lag spikes (with a bunch of desync issues) jumps greatly. It isn't limited to when large packs of creatures are on the screen, nor is it due to my skills, which are mediocre at best as I am a casual/softcore player.

Is there something different about Merciless in how the game loads or performs versus the other two difficulty levels? I can create a new character and play endlessly, but the higher in level I reach, the more likely I am to get kicked. Could it have something with server population at higher levels?

I tested it out today after getting kicked numerous times with my Merciless Shadow character. I went back two a very low-level Ranger and played very problem-free.

As stated, this isn't really anything new for me. Merciless doesn't like me for some reason.