I considered upgrading but then I read that it actually slows done your PC installing Windows 11.
I assumed the same thing. I just ran PCMark 10 on the same laptop, one with Windows 10 on the internal SSD and one with Windows 11 on the external $18.95 SSD in my $9.95 USB3 enclosure. The scores were almost identical. I am sure that your mileage will vary depending on your hardware and software setup. For about $30 you can find out how it would compare on your computer.
I am still not planning on switching from Windows 10 to 11 anytime soon, but I certainly will when Microsoft finally does stop supporting 10.