A regex should be faster

I would already doubt that a regex is faster than accessing array elements in normal circumstances, but here you seem to have missed the fact that the n-grams are made of words rather than chars. So your regex becomes: /((\w+\s?){3})/g where each char of (part of) the string are checked to find spaces. In IB2017's solution this is done once by the split.

I know it's possible in a single regex without looping over start by playing around with \K or similar

Look ahead assertions can help:

  DB<7> say for 'perlmonks' =~ /(?=(.{3}))./g
per
erl
rlm
lmo
mon
onk
nks
[download]

But it becomes cumbersome when working with words /(?=((\w+\s?){3}))\w+/g and probably not faster.

In case you want really want to include non-letters try unpack

unpack would probably be among the fastest solutions for character n-grams indeed.

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