by moosepuggle » 10. Dec 2019, 20:34
This finally worked for me after weeks of trouble shooting! Apparently, you need to turn off Beam Synchronization for running Yosemite or later on the guest. The sole purpose of the app BeamOff is to turn off Beam Synchronization to make a VirtualBox running Yosemite or later work better.
Download the beamoff app (this is my first post, so apparently I'm not allowed to post links, sorry!) in the VM, then run it in the VM. You want it to load on login, so go to System Preferences > Users & Groups > Login Items > then hit + and browse for where beamoff is located. On start up, the icon will appear in the dock, bounce a few times while it turns off beam sync, then close itself.
Host: Macbook Pro 2015 running Catalina
Guest: Mac Yosemite 10.10
Guest Setup: 1 vCPU, 4096 base memory, 25G storage, video mem 128Mb, EFI enabled, boot order: optical, hard disk, acceleration default, display scale 200%, VboxVGA, 3D acceleration.
Guest Additions 6.04 installed, then .dmg ejected
Note that I'm only running Circus Ponies Notebook as a lab notebook (why won't someone make a new electronic lab notebook that works this well?) on my VM, so not very intensive. My scrolling is still laggy, but mouse and display generally run much better!