The Twins keep lagging my modded terraria server

I have been playing on my own tmodloader server for almost a week now and my friends and I just entered hard mode. Everything was running smoothly so far, but when I summoned the twins my friends and I experienced unplayable lag. I tested other mechanical bosses like the destroyer and had no lag issues whatsoever. Also when I actually managed to kill one of the twins using a hacked character with stupidly overpowered gear the lag stopped completely.

Here is my mod list and computer specs...

The Twins keep lagging my modded terraria server