What is the fastest way to replace extra white spaces to one white space?
The fastest way? Iterate over the string and build a second copy in a
StringBuilder character by character, only copying one space for each group of spaces.
The easier to type
Replace variants will create a bucket load of extra strings (or waste time building the regex DFA).
Edit with comparison results:
Using http://ideone.com/h6pw3, with n=50 (had to reduce it on ideone because it took so long they had to kill my process), I get:
Which is indeed as expected,
Regex is horribly inefficient for something this simple.