Reverting BIOs to 1.8 fixed the issue.  
My XPS 8950 has been sluggish since mid December. I believe it has to do with the 1.9 BIOS update. I installed 1.10 and it didn't fix the issue. I did a system restore to a clean install of Windows 11. No improvement. I called Dell support and we went through all the basic troubleshooting steps. Only option here appears to pay for a technician to come out and look at it. Anyone else experiencing performance issue with the XPS 8950 recently? My system bios reports 1.10 being installed. Device Manager shows "System Firmware 1.9.0" under firmware along with 3 other firmware entries labeled "Device Firmware". Is this normal? I was thinking of using the BIOS recovery image for 1.10 to see if that could help? Any reason not to try this? Any other suggestions appreciated.
XPS 8950, performance sluggish, firmware related?