The Performance Should be Much better now. There seemed to be an issue with a bit of code in a physics process that would try to run even when the game slowed down which could cause a death loop. But that should be all good now.
Other Changes:
-Filters Buttons in Inventory and Craft UI can be shift clicked to inverse the filter so you can shift + click trinkets to search for everything not trinkets
-Filter buttons now darken when they are On
-Moved the Group inventory items from a button on the bottom of the Inventory UI to a button that matches the others on top of the Inventory UI
-Upgrading Fix - Equipment now correctly takes the right materials to upgrade instead of the equivalent of their crafting materials
-The Chance to craft an item for Free and Get a bonus upgrade is now capped at 50%
-Found some more missing localizations and took care of them.
-Should now be able to swap weapons from off-hand to main-hand from the equipment UI
-Auto equip items code more optimized
1.0.4! Performance Improvement!
Source: Steam Community (opens in a new tab)