Hi. I'm David, and I'm happy to help you.
To help me understand exactly what happened and give you the right solution, could you clarify these 4 points?
- What was happening with the PC back at the start, before you tried installing Windows 10? Was it already lagging or showing errors?
- When you went back to Windows 11 using the USB drive, did the PC work fine at first? Why did you feel the need to use the "Reset This PC" feature right after?
- Is this slowness happening all the time (even just opening the Start menu) or only when you open a browser or games?
- Press the "Ctrl + Shift + Esc" keys together to open the Task Manager. In the "Performance" tab, check if the CPU or Disk usage is stuck at 100%.
Also, what is the model of your Dell PC?
If you prefer, you can share a screenshot of your system information.
- Press "Windows + R", type
msinfo32and press Enter.
Maximize the window and use the shortcut "Windows + Shift + S" to use the screenshot tool.
Looking forward to your reply.