And Dave works for ATI now I guess ;)

On a GeForce 6800/7800, your vertex shader generates the following *native* code for the GPU:

401F9C6C 01CD400D 8106C0C3 60411F80    DP4    o[HPOS].x, v[OPOS], c[212];401F9C6C 01CD500D 8106C0C3 60409F80    DP4    o[HPOS].y, v[OPOS], c[213];401F9C6C 01CD600D 8106C0C3 60405F80    DP4    o[HPOS].z, v[OPOS], c[214];401F9C6C 01CD700D 8106C0C3 60403F80    DP4    o[HPOS].w, v[OPOS], c[215];401F9C6C 00400808 0106C083 60419F9D    MOV    o[TEX0].xy, v[TEX0].xyxx;

(The hexcodes are the 128-bit instruction words.) The "fixed-function" path produces exactly the same code, but with different constant register indexes.

If you want to do very accurate timing on the GPU, you can use the EXT_timer_query extension. If defines the following enums and functions.

#define GL_TIME_ELAPSED_EXT    0x88BFtypedef __int64             GLint64EXT;typedef unsigned __int64    GLuint64EXT;void glGetQueryObjecti64vEXT(GLuint id, GLenum pname, GLint64EXT *params);void glGetQueryObjectui64vEXT(GLuint id, GLenum pname, GLuint64EXT *params);

Use the glBeginQuery/glEndQuery mechanism with the GL_TIME_ELAPSED_EXT target to specify a timing interval. A call to glGetQueryObjectui64vEXT with <pname> GL_QUERY_RESULT returns the elapsed time in nanoseconds.

BTW, in case you're curious, your vertex shader produces the following native code on Radeon X800/X1800.

00100201 00D10002 00D10001 00D10005    DP4    o[0].x, c[0], v[0];00200201 00D10022 00D10001 00D10005    DP4    o[0].y, c[1], v[0];00400201 00D10042 00D10001 00D10005    DP4    o[0].z, c[2], v[0];00800201 00D10062 00D10001 00D10005    DP4    o[0].w, c[3], v[0];00F02203 01648000 01248000 01248005    MOV    o[1], R0.0001;00304203 00D10041 01248041 01248045    MOV    o[2].xy, v[2];

The ATI driver inserts an extra instruction to move (0,0,0,1) into the primary color interpolant, but otherwise, it's the same native instruction sequence that Nvidia hardware uses.