In our last meeting, we have talked about some performance goals for a future version:

• Speedup evaluation of simple algebraic expressions to values close to sympy (5x faster than Mathics 4.0)
• Load Rubi in less than 2 min.
• Run the full CI in less than 5 minutes.
• Other ideas?

Ideas to reach this milestone:

[ ] Improve internal structures, like store Attributes to bitsets instead of strings (PR #81), replace certain properties implemented as method (like is_atom) by class variables, etc.
[ ] Add primitives for symbolic Arithmetic (Expressions like Plus[a,b,c] could be represented by InstanceableBuiltins).
[ ] Improve the routine that decides in which library certain symbolic evaluations are delegated (PR #33).
[ ] Implement some kind of pre-compilation over complex expressions.