Fbneo was updated to include the new accurate blitter delay function that MAME implemented. I haven't tested it on my Pi 4 yet, but from what I've read, it seems every CV1k game just needs CPU set to 50% now. I'll report back with my personal experience once I have a moment to test them.

https://github.com/libretro/FBNeo/commit/ba134d1c7f1d5bb57be7ec8e4056ad743c27353c