I've just had a quick look through at the performance by race code and there aren't huge differences between them although PR (WA Races) does seem to perform the best by quite a bit, particularly the top 3 raters. However I also think there aren't enough races recorded yet so its probably something I need to come back to.

For interest I also just checked the performance by day, turns out weekdays do ok, not bad not great but saturdays are the best day by far which is interesting, I thought it may have been the worst.