I recently acquired an ancient (2008) HP DC5750 with the intent to turn it into the router for my home network. The guy I bought it from had taken the effort to install Linux Mint on it. I suppose he did this so he could show that it worked. Kudos to him for that. Of course, I had to play with it to see what it's like. And I was quickly reminded of why I abandoned Debian/Ubuntu/etc in the first place.
I ran the battery of benchmarks provided by the "hardinfo" program on both my laptop and the HP. Given the age of the HP I was somewhat surprised that it performed 2-3 times as well on the benchmarks as the laptop. But the big surprise is just how poorly the HP performs regular tasks. It takes longer to boot, to open programs, to do pretty much everything that isn't a benchmark. This really taught me just how much an OS and DE can get in the way of a CPU. Just thought I'd share this little experience.
I'm currently in the process of switching the HP over to Hawaii. I want to see how a Wayland desktop compares to X.