UX improvements for leaderboard rankings table: reduce granularity of score

On the leaderboard rankings, for example at https://www.gpumode.com/leaderboard/340, the score has lots of digits, for example 16465.310μs. Only a small number of these digits are needed to tell that this score is better than the next best score of 16908.299μs. This display ends up being visually confusing.