Multiple-tab web browsing really slow on Whonix - virtualbox

I have a system with 32 GB of RAM and I have set Whonix Workstation to have 16 GB of RAM in Virtual Box, but it doesn’t seem to use more than 4.5 GB of RAM. Yet when I have multiple tabs open on Tor Browser the system becomes insanely slow.

Anyone know how I can fix this situation?

Whonix doesn’t develop Tor Browser.

Bug Reports, Software Development and Feature Requests chapter Generic Bug Reproduction in Whonix wiki required.

You would need to reproduce this on Debian (in VirtualBox) and then report a bug upstream for Tor Browser against The Tor Project.