I have just measured the amount of time a Pentium 133 needs to compute
a satellite position (RA/DEC). This is with Dr. Kelsos Turbo Pascal code,
implementing the full SGP4 model of satellite orbit propagation.
The result is 15s for 36000 positions or about 2400 positions/s. This
includes reading and writing files and a nonoptimized reference
implementation with an inefficient compiler for numerical computations.
An optimized C implementation without the file i/o overhead should
easily reach 10000 positions/s. Mel's programm needs to calculate a
new position at 18.2Hz. The C code for the implementation of SGP4 is
in the public domain. One more switch in DoAProcessTimedToBiosClockTick()
would to the trick at every tick :-)

Markus Kempf