Quadrilla Bug - Massive Frame Drops

Newly encountered bug since latest update:

My wife and I play together on two separate PCs, and we experienced what felt like network latency/lag, but which turned out to be massive frame drops when running a Savannah map this evening. The frame drop was proportional to the number of Quadrilla enemies on screen at a given moment - if they moved or jumped, it would cause enormous frame drops (down to a low of just 8FPS for a large pack of quadrillas). If only one player had them onscreen, the other play was not affected, of course. And we tested it kiting several packs of quadrillas - in each instance, noticeable frame drops from even a single quadrilla at a time, but enormous frame drops if multiple quadrillas were active at once.

No effect from mobs of other enemies, no matter how many enemies at once, or how much active effects at once. The problem was confined entirely to Quadrillas, and has only occurred to us since the most recent update.