I've tried, and honestly, on my low end hardware, only Arch seems to be the smoothest. I'm running EndeavourOS, which is working amazing smooth here. Fedora always freezes for minutes when the RAM is full. I'm thinking maybe it's ZRAM fault here? And yes, I even tried creating a SWAP file together with ZRAM and no luck.

On Arch it uses zswap....

I wanted to use Debian, but too old packages for me... is Debian testing stable enough?

It is less zram, and more block I/O scheduling congestion on Linux in general[1]. The machine thrashes and becomes unresponsive under memory pressure as I/O requests flood the disks, whether it is for swap, or unpaging and re-paging file-backed storage (open shared libraries, etc.), or simply evicting frequently accessed files from the file page cache.

I run my personal workstations and laptops without swap, and with earlyoom[2], which results in applications getting killed before the machine reaches unresponsive state. I can only afford that because I trust my tools (vim, emacs, firefox, but most likely firefox) would not lose my session if they shutdown unexpectedly. I turn earlyoom off when I play games where I know memory usage will grow suddenly, but the game won't reach the limits of my machine. You can also whitelist specific applications in earlyoom, if I recall correctly.

Some people claim success configuring the kernel to use different I/O schedulers, but I haven't tried that yet.

[1]: https://lwn.net/Articles/682582/

[2]: https://github.com/rfjakob/earlyoom