Linux Bugs (Ubuntu 11.04)

[suicvne]

I recently installed this because I could not play Minecraft under my Linux installation. While I do have Windows alongside Ubuntu, sometimes I feel like using Ubuntu over Windows. I couldn't play Minecraft under Ubuntu because the lag was just unbearable! (5 fps Linux, 50 fps Windows). So, I went for this game.
It looked promising, it performed slightly better (20 fps, jumpy. bearable though). I was excited. So, I booted up the game and played for about five minutes. After that, it just randomly closed on me. After running through Terminal, this was the only message I received: Segmentation fault
I have no clue what this means and it only happens through Linux. I don't have a Mac to test it through to see if its just Linux or what. I have some specs for you guys also
Minetest version: 0.3.1 AND Latest Dev Build (Dec 9) both cause this problem. I have tried deleting every trace of Minetest from my system and reinstalling it but alas, no luck
Ubuntu 11.04 under GNOME (I have Unity but it causes too much lag for games). ATI Radeon x300 Graphics card, (sound doesn't matter)
Minetest listed my OpenGL Version as 2.1.

Again, I did NOT have this problem under windows at all. In fact, I could probably play for hours! Any solutions guys? Thanks in advanced,
Mike

PS, while I'm here, what tips do you reccommend for boosting the speed of this game? :P

[celeron55]

Probably bad video drivers on Linux.

[Canisaur]

I'm running Ubuntu 11.10, and I wasn't having the bad FPS issues (using an Nvidia card with Nvidia linux drivers), but I WAS having the issue where it crashed after a couple of minutes when I tried this a month or so ago. Now I no longer have that issue.