Bad performance after upgrading to Linux Mint 20 (Ubuntu 20.04 based). Solved by disabling transparent hugepage in kernel.
The grub approach survives a restart:
Find and replace GRUB_CMDLINE_LINUX line to:
Update grub and reboot:
Updated Oct 4, 2021: if using Windows guest, also use OpenGL render to avoid high CPU usage. Edit *.vmx file and add: