Never say "fastest" because at some point it may not be (or possibly for specific situations) and someone else may end up having the "fastest" of that kind of module instead.
Just call it "fast" and point to legitimate benchmarks (containing module versions and current date/time) that show that it's faster compared to similar modules.
I appreciate your breakdown of the steps you went through, very straightforward in the incremental improvements.
Although, you may want to reconsider your usage of function.length to determine whether to use monadic vs variadic. There are some gotchas that may cause inconsistent results => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/length.