There are a lot of HTTP servers out there besides Apache. Many of them even have features that Apache does not have or doesn't support well. Some are smaller and leaner to run on modest hardware, some are optimized for dynamic content, and so forth.
Switching webservers, or even starting from scratch with uncommon software, is not without its risks, of course. Support can be harder to come by, and how-to knowledge is rarer. A lot of open-source projects are obscure for a reason, too - they don't work well. But a little research can pay off handsome security dividends in the long term.