Which GPU do you have? Which drivers are you using? are you sure you’re using those drivers and they’re not just installed but unused? My first guess is that you have an Nvidia and are using open source drivers (nouveau).
Some performance difference is expected, after all most games are being run through a compatibility layer, and many others were ported as a second thought so they’re not optimized on the same level. Also note that lots of us don’t use Windows, so we’re not comparing experiences, if it runs at an acceptable frame rate with an acceptable graphics settings for what I would expect the GPU to be capable of, then I don’t bother benchmarking it.