a lot of the problem is that so much time seems to be spent before each race with the riders digging up their gate positions... if you were sad enough to sit there at a meeting and time them at how long they are in the start gate vicinity, it would probably be longer than each race takes!
the races last for 1 minute... how can they struggle to fit in 15 minutes of racing into a 2 hour slot???
maybe the referees need to get a push on or cut out the digging.
i don't know if he still refs but i always thought Frank Ebdon was the best ref at keeping things moving.