oh— for regex performance Perl blows Swift, Java, Python, Ruby, Go, and C++ out of the water. For simple string manipulation— substring replacement, string reversal, etc. it's never the worst but never the best. Scroll down to the bottom of this paper where they test actual regexes though and the difference is pretty stunning.

http://jultika.oulu.fi/files/nbnfioulu-202001201035.pdf