Speed up

[whilp]

Per @anachronistic:

so - i did a couple of benchmarks on the lib and found differing speeds + heap allocations depending on the incoming string
and i believe that it's possible to 1) normalize the speed to within reason (i.e. longer strings will naturally take a bit longer to parse), 2) normalize the allocations (i believe you can produce a 0 allocation lib if you write the parser yourself)
i did a shit proof of concept and for local paths i had it down to 150ns / 0 allocations by having a Parse method that accepts a pointer to a net.URLstructure ... ex func Parse(url string, handle *net.URL) error { ... }
that was leaning mostly on strings.Index which reports first appearance of a pattern, so ex. colon := strings.Index(url, ":") ... slash := strings.Index(url, "/") ... return colon == -1 || (slash & slash > colon)
so file:///whatever and /foo/bar/whatever returned true very quickly
it gets a touch more complicated from there, but yeah: that's my challenge to you ... normalized speed (for some reasonable definition of normalized compared to string length) and 0 allocations (or at most 1 if you don't like the C-style of passing in the structure)