Host performance is a joke after the Eye of the Storm update

I tried the Eye of the Storm update in the beta branch, and notice that my local host ( just me ) has a terrible performance, especially during moonstorms. So bad that I couldn't even pick the tools. I thought maybe it's a beta problem.

Then the update was rolled in the main branch, and the same story. I literally can't move when there's a bunch of bees or mobs around. Host performance is always either red of yellow. 

The game also ran out of memory a few times and crashed, even though I have 16GB of RAM. Although I turned off pagefile, but even so, half of my RAM should be more than enough. I'm using a decent CPU ( 8x3.6Ghz ) so this should not happen.

The patch before this ( the one that reduced the loading times ) was so great. I don't know what happened here.