Remember the need for stack (2000000 I use).
Some tips:
cg_lagometer to 0
r_vertexLight 1
r_primitives 0
Of course always care about whatever could reset the renderer: Still no fix.
Now it has the option for depthbits on "r_colorbits". The default is 0 and that switches to 16 but other values can be used 15, 24 or 32 (if they work on your system).