Alternation in regexes seems to be terribly slow in big files

Question

I am trying to use this regex:

my @vulnerabilities = ($g ~~ m:g/\s+("Low"||"Medium"||"High")\s+/);

On chunks of files such as this one, the chunks that go from one "sorted" to the next. Every one must be a few hundred kilobytes, and all of them together take from 1 to 3 seconds all together (divided by 32 per iteration).

How can this be sped up?

Answer 1

Inspection of the example file reveals that the strings only occur as a whole line, starting with a tab and a space. From your responses I further gathered that you're really only interested in counts. If that is the case, then I would suggest something like this solution:

my %targets = "\t Low", "Low", "\t Medium", "Medium", "\t High", "High";
my %vulnerabilities is Bag = $g.lines.map: {
    %targets{$_} // Empty
}
dd %vulnerabilities;  # ("Low"=>2877,"Medium"=>54).Bag

This runs in about .25 seconds on my machine.

It always pays to look at the problem domain thoroughly!