Years ago, I used a slow 512 MB SD-card to support my Linux OS when it only had 4 GB RAM. Despite being slow, it freed up some more RAM by storing data that wasn't needed. So it helped to run everything I needed. But what I should have done was just buy and add 8 GB RAM. It's the same as switching to SSD: you don't want to go back

In this case, you could try to put Bitcoin Core's chainstate directory on the USB-stick. That directory is less than 5 GB, and it's much more demanding from your HDD than the (much bigger) blocks directory. I just don't know if (and how) you can move one directory to a different device on Windows.