[NAME]  - Don't think it's fair to compare Win 10 and Win 11 PCs. Did you do the BIOS update or did this PC come with BIOS 1.10.0 installed?  A bad BIOS update could cause this kind of issue. See this thread.  Have you opened Apps>Startup and disabled all the stuff you don't really need loading at every boot? And have you looked on Startup tab in Task Manager to disable other non-essential stuff that loads at every boot? Are you using McAfee which may have come pre-installed, either as 30-day trial or as a 1-yr subscription? McAfee has been known to cause poor performance.  Best way to uninstall it is using McAfee's own removal tool, by following Option 2. If you think you might want to reinstall McAfee after testing without it, make sure you've registered your free trial or subscription as mentioned at that page, before you uninstall. That way you can download and reinstall it again for free for remaining balance of the trial or subscription. When you uninstall McAfee, Windows Security (AKA: Windows Defender) should be automatically activated, so confirm that it's running and use Windows Update to get latest signature file. Have you opened the Advanced Settings screen for the active Power plan and made sure Processor Power Management is set to Max=100%? Up to you to decide if Min=100% is appropriate for your usage.
Purchased this Dell XPS 8950 desktop as an upgrade to 3 year old Dell XPS 8930. They have the same amount of RAM (16GB). This new XPS 8950 is so slow compared to 3 year old Dell XPS 8930. Opening file, opening software is at least 50% to 80% slower than the 3 year old XPS 8930. What is wrong with the Dell XPS 8950?
XPS 8950, extremely slow