Windows pc 100% disk on Parallels 10.04 and 2020 iMac 3.7GHz

Hi,

I recently upgraded my 2014 MacBook Pro Retina i7 which ran a Windows 10 PC in Parallels 10.04 no problem. Fast and smooth. I now have a 2020 brand new iMac 3.7 GHz with Radeon Pro 580X 8 GB graphics. I installed a fresh copy of Windows 10 and a new Parallels install. However on my much newer, faster iMac, my windows machine is unusable. On looking in task manager, the disk is maxed out at 100%.

To counter this, I moved the pvm from the internal fusion drive to an external ssd with better R/W speed. Still the Disk utilisation is maxed out at 100%.
All fresh installs on a brand new 2020 iMac. I appreciate it's an older version of Parallels, but I previously saw no reason to upgrade because it was working so well for what I needed.