TieRankingLeaderboard takes a lot of time to rank_member

[prcongithub]

I am using TieRankingLeaderboard to rank learners based on some score with some member data.

This worked really well initially. But as the number of learners grew, its taking a lot of time to update ranks for members.
The score which is used to rank members keeps changing frequently.

Is there a way to improve performance here?

The leaderboard has about 12000 members. Its taking more than a minute to rank members now.