You may wish to try: (one at a time)
- more compactors
- more levels
- no compression
I am not sure if snappy is the default in leveldb but it is in badger. I have seen other posts here where more levels helped giant databases. The idea with more compactors is maybe compactions will be smaller and happen more concurrently.
Also you may want to peek at the index cache and block cache metrics - see if they are helping you at all with your write heavy pattern or not