When you decide to try out Sauerbraten you should be aware of your operating system, your current graphics chipset (manufacturer and card name) and that this project is still "Work in Progress" (WiP)!
Typically, to run Sauerbraten at playable speeds on minimum settings, you'll need at least:
1GHz or higher CPU, 256MB RAM and a GeForce 4 MX or equivalent GPU.
For maximum settings, you'll need at least:
2GHz or higher CPU, 512MB RAM and a GeForce 6600 or equivalent shader model 2.0 GPU.
Before you even download Sauerbraten, make sure you meet the above requirements and have the latest video card drivers installed for your OS. If you're on Linux, make sure you're not using MESA drivers, and if you're on Windows, make sure you're not using the generic drivers.