is it also possible to run C programs
Sure, you can run C programs. You won't be able to compile them on the box though as there are no compile tools in the OS. I suggest you read https://wiki.libreelec.tv/development-1/build-basics and familiarise yourself with how our distro is packaged. If you want to develop things we are probably not the distro you're looking for 
Sure, you can run C programs. You won't be able to compile them on the box though as there are no compile tools in the OS. I suggest you read https://wiki.libreelec.tv/development-1/build-basics and familiarise yourself with how our distro is packaged. If you want to develop things we are probably not the distro you're looking for
which distro would you advise? i checked out several of them and noticed that libreelec with kodi is one of the only ones that can play 4k video's smoothly. Other distro's like rasbian 32 bit have issues with playing 4k mp4 files. I already tried changing cpu speeds and gpu mem to max.
The official Raspberry Pi OS shouldn't be far behind LE in terms of playback; the Pi Foundation devs use LE as a testbed for media things and then backfil the required firmware, kernel and ffmpeg changes once things are proven. If they are lagging behind you should also be able to self-update key packages to use the same source versions/patches that LE runs .. to achieve a similar experience.
NB: It's not impossible to develop things with LE, but the workflow of updating sources, updating a package, rebulding the image, updating the OS .. is less intuitive to developers who are often used to fiddling with code, building, and then running code in-situ.
