I am playing with 40 mods, and I had finished making a beacon. Upon inserting the iron into the beacon, and selecting haste, my game started to lag to the point that I was at 1 fps. It then crashed. I tried updating my mods to the latest version, I tried reloading the world multiple times, but it doesn't work.
https://pastebin.com/d4sJ5tFU crash report
https://pastebin.com/bzL1EJ57 log