So far, I encountered "Warband has stopped working". I have a decent computer so I don't think it crashed due to a lack of memory. As far as I know, Warband uses only 2Gb of your RAM, because it runs on a 32-bit engine. I suspect you'd have to limit the usage of resources in the mod, especially by making sure it doesn't load unused Native resources. I checked "module.ini, and it looks like there is a problem on this side.
Edit: Couldn't find an exact solution to this. I commented off the unused resources, but I still get crashes. I tried ticking "load textures on demand" on/off, and realized that it is better to have it on, but it still crashes a lot. Next, I'll try enabling the edit mode. It might seem strange, but some mods advise to have it on.
Edit 2: Tried that one too. Nope, it crashes even faster.
Edit 3: You might want to look into "Automatic shadow recalculation", which is a distinctive PW feature. I noticed that people aren't crashing individually, but in groups, which means that there is a certain resource-intensive feature that activates periodically, thus forcing some people to crash. The shadow auto-calc might actually be the reason, because it activates for all the pleyers at once.