Points appear to be based on thousandths of seconds. For example, my last race was 27min 40secs. 27x60+40=1660 seconds. x1000 for thousandths of seconds = 1660000. The points for this race were 1660078.
The percentage appears to be [1st place’s time] / [your time]. For example, 1st place in B cat is currently 1:52:42 (6762 seconds) and my time is 1:56:50 (7010). 6762/7010 = 0.9646 which written as a percentage is 96.46%.