I'm using the MetroLight - Light Theme (default?) in Themes Manager.
But joy, joy! Using the #VirtualMachineArgs: -Dprism.order=sw worked.
Just for reference for anyone else that ran into the speed issue in the IDE in a virtual machine (vmware)
1. I've changed the CPU settings from 1 CPU, 8 Cores -> 1 CPU, 2 Cores (counter intuitive, but it seems vmware starts using emulation of cores at a certain point, which slows down the emulator)
2. Made sure the Memory is not above the maximum setting (changed it from 16GB to 8GB, again some swapping occurs otherwise)
3. Disabled 3D acceleration
4. Added #VirtualMachineArgs: -Dprism.order=sw in the B4J app.
For me, this results in a much smoother IDE in vmware, AND I can still run the UI apps.
I hope it may be usefull to someone else.