I switched from Nixos to void Linux. Here's my experience so far.
I hopped from arch (2010-2019) to Nixos (2019-2023). I had my issues with it but being a functional programmer, I really liked the declarative style of configuring your OS. That was until last week. I decided to try out void Linux (musl). I'm happy with it so far.
Why did I switch?
Nix is extremely slow and data intensive (compared to xbps). I mean sometimes 100-1000x or more. I know it is not a fair comparison because nix is doing much more. Even for small tweaks or dependency / toolchain update it'll download/rebuild all packages. This would mean 3-10GB (or more) download on Nixos for something that is a few KB or MB on xbps.
Everything is noticeably slower. My system used way more CPU and Ram even during idle. CPU was at 1-3% during idle and my battery life was 2 to 3.5h. Xfce idle ram usage was 1.5 GB on Nixos. On Void it's around 0.5GB. I easily get 5-7h of battery life for my normal usage. It is 10h-12h if I am reading an ebook.
Nix disables a lot of compiler optimisations apparently for reproducibility. Maybe this is the reason?
Just a lot of random bugs. Firefox would sometimes leak memory and hang. I have only 8 GB of ram. WiFi reconnecting all the time randomly. No such issues so far with void.
Of course the abstractions and the language have a learning curve. It's harder for a beginner to package or do something which is not already exposed as an option. (This wasn't a big issue for me most of the time.)
For now, I'll enjoy the speed and simplicity of void. It has less packages compared to nix but I have flatpak if needed. So far, I had to install only Android studio with it.
My verdict is to use Nixos for servers and shared dev environments. For desktop it's probably not suitable for most.
You mean in terms of how fast it feels? I have never heard anyone saying this before. Can you share some details and perhaps some tips to improve performance on Nixos?
What hardware do you run Nixos on and do you modify and rebuild a lot of packages on nixpkgs?