Performance optimization (improve efficiency / runtimes / memory usage)

[jwmueller]

Try to speed up the runtime of this library on large datasets. This can be done via:

• speeding up individual checks
• reusing more computation across checks
• using parallelism

This is a great issue to get started contributing to this repo! There are many ways to achieve speedup (speeding up individual checks will be the easiest). It is easy to verify speedup via basic benchmarking that also ensures the results remain the same.