I did the Gentoo thing a few years ago. It was a lot of work to get up and running and as you say, I didn't see any real noticeable speed difference over Slack. ArchLinux was pretty nifty and I played with it for quite awhile. I just didn't like having a different file hierarchy and placement of packages than Slack. I also had more problems compiling apps. It was just a matter of what I was used to. Setting up the inits manually was fun though.