Any updates?
My server is basically unusable because of this bug. It flip-flops between being bugged for 5-8 hours, then is fine for another 5-8h ... and then bad again.
I have exactly same problem. IOMMU is off in my case and I have no VMs running. I rebooted twice yesterday, but today it's slow again.
alexandria-diagnostics-20200619-2224.zip