Reference tracking is one of the major reasons for slower performance of Bonsai vs classic. There are several complimentary ways to approach this problem:

• Reduce the number of call to functions that use reference tracking (for instance to constant folding).
• Reduce the number of calls to reference tracking.
• Make reference tracking faster by itself.

This task is about the latter approach. The main reason why reference tracking is slow is the use of hash-maps and hash-sets, therefore this task is about analysis of the existing code, and replacing hash-based data structures with a custom-designed and more efficient data structures. Since the most efficient way to operate on sets of objects known to us is via bitsets, this is what we will focus on.