Performance tips when using regular expressions (regexps) in font-locking

[Nordlöw]

I have enhanced my cc-mode with extra font-locking for assignments,
function calls, numerical literals, operators and even format strings
to the [sf]?printf-functions. The regular expressions describing these
context are quite complicated and as a result my cc-mode is no longer
as snappy as without my enhancement. Does any have any tips on how to
write regular expressions when performance is crucial? For example
should I use [:space:] instead of [ \t]? Should I post the code
aswell?

Thanks in advance,
Nordlöw