Source Insight allows you to augment a language with your own custom parsing regular expressions. You can edit these expressions by right clicking on a source file and selecting Language Properties.
If you have too many expressions, or you are using a regular expression that is inherently slow to match, you may notice that it takes a moment or two to parse your files.
A regular expression can be slow to match if it starts with a pattern that is easily matched, but ends with a pattern that often does not match. For example:
[a-z]*(\([a-z]+\))
This expression will be slow to match because the pattern starts with [a-z]*, which means, “match any zero or more alphabetic characters”. Most characters in a file will potentially match.