Dorico 4 is so slow

Recently updated from Dorico 3.5 to 4.2.0. Half way through the project, and it is slowing down considerably, to the point that it is unusable.
I am on Windows also. I have basically closed everything and am just running Dorico. My computer is fairly new and powerful, happy to share specs if needed.
Tried following all the tips above. No use. It has been slowing down over the past few days, but as of last night, it has slowed down to unusable pace.
What is my solution here? Is it safe to switch back to using 3.5 mid-project or will that mess with things?

Edit: I should add that the problem is significantly more pronounced when I start entering lyrics. Lyric entry is so slow, it is nearly impossible.

I have this week been making edits to a large score (120 pages) from last year and 3.5. I’m on Mac, and I notice lyric entry being considerably slower than before, which I guess must be related to the new lyric handling via paragraph style. (FWIW, I haven’t noticed any visual differences, so that’s nice.)

I like to type, and hyphenate, lyrics in a text editor and paste them in. Unfortunately this is pretty much as slow as typing them in Dorico – each Paste taking a second or two. At least Dorico doesn’t lose any of my keystrokes as I Paste and Space, so I can get way ahead of it if I don’t make any errors. Today I started using the extra time to proof my entry bar-by-bar against the markup score, while the lyrics were pasting in.

I’m sure more optimizing of the code is possible once they decide they’ve got enough bugs fixed (and not before!) Already I have seen several kinds of operations speed up since 4.0 in January.

I am, also, working with a very large 50+ page orchestral score. I ended up messing with every setting on my computer that I could find, and somehow, I have improved it considerably, and can use it again. It’s still slow, but it’s usable slow. I don’t know what fixed it, but I removed every startup application that I could find. Removing “Dolby access” from my computer, which I was not using, but I think it was still doing something in the background. Removing Realtek audio from startup. I think one of the latter two must have made a difference there. I don’t know. I am just glad I can keep working now.