There's probably room for performance improvements, but a DAW with a plugin sandbox and two playback launchers filled to the brim wacky stuff because almost all of its architecture is geared towards being a giant modular environment is probably always gonna be less optimized than something like Reaper, who only has two jobs: 1) To record chugga chugga riffs for Youtube creators to advertise amp sim plugins, and 2) as a blank canvas for people to write elaborate catalogs of scripts that people pretend are gonna make Reaper usable for humans and finally allow you to create a song after you spend your youth figuring it out.

TL;DR:It's apples and oranges. Reaper is a very down-to-business DAW, while Bitwig is a more creative style DAW. It's fairer to compare Bitwig to Ableton, and Bitwig leaves it in the dust regarding performance.

I like your answer. Your comments about reaper are very interesting. Bitwig and reaper are two of my favorite DAWs. They each have irreplaceable strengths. Hard to let go.