Would you elaborate on why you think compilation on Guix is slower than Gentoo? Thanks.
Compiling guile from scratch was, by the way, insanely slow, and because I struggled to get Guix working right on my first try, I had to compile it over and over again, which took about a day each time. A "guix pull" took four hours on my system, and I had to do it twice each time, once for root and once for my own user. My first "guix pull" took two weeks due to all the errors, toubleshooting and restarts the process took as I tried to get Guix working as it should.
In addition, it seems that Guix packages don't have optimizations enabled, which is a deal breaker for me, as optimizing the packages I install is a significant reason I compile them from scratch in the first place, as I'm running on an old, slow machine which could use all the performance boosts it can get.
Finally, I might have a broken environment on my system which makes compilation even slower still than it otherwise would be, but until I get it fixed I have to live with it, and so for all of these reasons compiling everything from scratch on Guix is just not practical for me right now.
Maybe with a newer, much faster machine I'd be ok with it.
I'm coming from Gentoo myself, and I've tried to get Guix working on Gentoo a couple of times over the years, and have always been frustrated by how much work and hacking was involved in doing so. I'm no Linux novice, either. I've been a professional Linux/UNIX admin for decades, I know and love Scheme, and am no stranger to putting in a lot of work to get something to run on Linux, but I failed in two major attempts with Guix, despite having lots of thorough assistance from Guix developers on #guix on IRC.
So back to Gentoo's package manager I went.
A typical user would not have put in nearly that much work to trying it out, nor would they have had the skills or knowledge to get nearly as far as I did. Though, to be honest, I did have some requirements (like doing my own compilation of everything on my own old, slow laptop, just as I'd been doing with Gentoo, and not trusting their binary distribution) that a typical user would not.
The other lesson I got from my last attempt was that trying to compile everything in Guix from scratch on an old laptop is just way too slow. Doing this on Gentoo is slow and painful enough, but it's way worse on Guix, and simply unworkable. You really have to have a fast, modern system (or offload your compilation to another machine which will crank away for weeks on end and that you can then download the binaries from) to constantly compile everything you need for Guix.
That said, Guix has really come a long way over the years, and it's impressive to see how far they've come, and I'd absolutely love to see them succeed, but they've got a long, long, long way to go.