0.8 promises better performance, besides a bunch of other improvements:
https://github.com/gwicke/pegjs/blob/master/CHANGELOG.md
At a minimum, we'll need to change all references to pos and pos0 to peg$pos etc, and also rework the cache key patch regexp in mediawiki.tokenizer.peg.js.
Also relevant:
"Removed the toSource method of generated parsers and introduced a new output option of the PEG.buildParser method. It allows callers to specify whether they want to get back the parser object or its source code."
Version: unspecified
Severity: enhancement