[NAME]   - My immediate thought is Dell's SupportAssist and/or Dell Update services are running in the background, both of which can cause lags on this PC model (lots of threads about this issue!). Go to Start>Run>services.msc.  If those services are running, set the Startup type to disabled for all of them and reboot. See if that helps. (You don't need any of them, and you can always check for updates manually using your Service Tag at the Support site.) Disabling those services stopped the lags on my XPS 8930 which has the same config as yours, but only 16 GB of RAM. What else is automatically loading at startup that's unnecessary junk? Look on Startup tab in Task Manager. Did you install extra RAM? Yours has 48 GB, but that's not listed as a supported RAM config in the Service Manual. That doesn't mean 48 GB won't work, but since it's not listed in the manual, Dell hasn't validated that amount of RAM, and that might be an issue. And what's your actual RAM config? What version of BIOS is installed? The latest is v1.1.15. Are all your other drivers up-to-date? Do NOT let SupportAssist or Dell Update manage a BIOS update. Update BIOS outside Windows, from the F12 menu. You didn't mention which SSD you have, but Dell has some recent  (2020) firmware performance updates listed for the various brands of SSD installed in the XPS 8930, so make sure yours is up-to-date, if it's listed. And there's also a firmware update for a Seagate 2T HDD, if that's the one you have...
I have a Dell XPS 8930 desktop =Intel Core i7 Processor M.2 512GB PCIe x4 SSD + 2TB 7200 rpm Hard Drive48GB DDR4 2666MHz UDIMM Non-ECCNVIDIA GeForce GTX 1660Ti 6GB GDDR6Windows 10 Home 64bit English9th Gen Intel Core i7 9700 (8-Core, 12MB Cache) I have been using Dell for 18 years. Loved them until this new computer I got in May 2020. Right out of the box, it is the slowest computer I have ever had. I wish I sent it back while I still had time. Their tech support hasn't helped at all. I am hoping someone here can though. The computer lags even when I only have ONLY simple programs like Notepad open. I have 48G of RAM, but it is brutal. The cursor doesn't even keep up with my typing. I don't have programs like Photoshop open. Task Manager doesn't show anything slowing it down. My anti-malware software has always been ESET's protection. I would really like to stay with Dell, but this single computer changes that.
XPS 8930, slow, delays, etc.