I got curious and tested this on my new setup aswell.
I use "vanitysearch.exe -stop -gpu bc1q....." and I'm getting 2200 Mkey/s on my 4060TI paired with an i7 14700k (undervolted).
However my CPU is at 100% usage and my GPU shows 1-2% in task manager. Is this normal or is my gpu not putting out enough work here?