What I do for my handicap Radeon X300/Intel Pentium 4 computer:
1. Set to fullscreen borderless
2. I use 16:9 or 4:3 screen ratio so I set resolution to 640:480, 800:600, or 1024:768
3. Turn settings in graphics as low as possible (No shaders)
4. Render distance 50
5. Anistropy to Performance