Replace String#split("") with direct character access
Replace String#split("") with direct character access

The scanner class performed a lot of split calls on a static string in
order to access individual characters, which can be done through
String#[] instead avoiding expensive method calls and creation of
transient objects.

On a complex filtering case, String#split was taking 79.12% of the
runtime and is now negligible at under 1%.

ploubser/JSON-Grep