Performance issues are the complaints you hear most often about Lightroom. Over the years some engineers have attributed the cause to the programming language Lua that the Lightroom team inexplicably chose.
The problem is probably magnified by the fact that Lightroom users tend to process large batches of photos. I'm curious if that is the case with you? Photoshop is usually used to do a lot on one file.
When I see open letters like this one about Lightroom performance I naturally guess it is from a wedding photographer or some such.