I also reduced the display scale factor from 200% to 100% and selected the 'VBoxSVGA' graphics controller. Gscelsi wrote:I am using macOS Catalina 10.15.2 on MacBook Pro 13-inch 2017, VirtualBox 6.0.18 running Ubuntu 19.10 Thank you so much! gscelsi Posts: 2 Joined: 9. Now in full-screen mode, with 'auto-resize guest display' selected, on my 13-inch MacBook Pro screen the Ubuntu display settings show 1440x900 and everything looks good and works fast. I left the VB manager in full resolution. You need to right-click on '/Applications/VirtualBox.app', choose 'Show Package Contents' and navigate to the 'Resources' folder, as shown in the screen shot posted by 63BottlesOfBeer. Note that the 'Open in Low Resolution' flag must be set on the 'VirtualBoxVM.app' file, not on the VirtualBox manager. No need to lower the resolution of the entire Mac. System is no longer impossibly sluggish and audio no longer crashes even using multiple sources at the same time. The instructions from 63BottlesOfBeer on 27 Feb.

I am using macOS Catalina 10.15.2 on MacBook Pro 13-inch 2017, VirtualBox 6.0.18 running Ubuntu 19.10

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