The crash seems located in the nouveau drivers. Try the nvidia ones.

Read this article about how to keep both drivers without conflicts.
https://wiki.archlinux.org/index.php/Nouveau#Keep_NVIDIA_driver_installed

Hmm now my audio has started to stutter and makes a really annoying crackling sound. Annoying as was working fine yesterday.

Anyone experiencing anything similar?

Seems to be working properly again! No more crackling sounds in the audio test feature. I'm currently using version 1.4 after I downgraded from 1.5.

Any tips on how to optimize performance, frame rate drops a bit too much on any resolution higher than 640x480.

You can try sfall for fallout 1. It should allow of using directx instead of ddraw.
It crashes to me, so be sure of backing-up the original ddraw.dll so you can revert if you have the same problem.


http://koti.mbnet.fi/ton_hur/files/fallout/sfall1.7z

Edit: I tried again, actually it does not crash. But the fading transitions are very slow. The game itself maybe goes a little better, but I am not sure.