lighttpd is one of the fastest webservers available, especially with aio. There are a lot of other fast and lightweight webservers but lighty is the most common.
I've developed a few modules for lighty (still not public) and saw a little facility to get more performance. The performance-gain is relative small in this case but why should we give it away?
Run the following two lines in your source directory before you compile your lighttpd webserver:
find . -name "*.c" -exec sed -ie 's/buffer_append_string\(([a-z0-9_]\+,[[:space:]]*".*")\)/BUFFER_APPEND_STRING_CONST\1/g' {} \;
find . -name "*.c" -exec sed -ie 's/buffer_copy_string\(([a-z0-9_]\+,[[:space:]]*".*")\)/BUFFER_COPY_STRING_CONST\1/g' {} \;
Who would like a little explanation: I think this is only an oversight because in most cases the main developers of lighty use BUFFER_[APPEND|COPY]_STRING_CONST which is a macro for constant strings. In some cases they use only the dynamic equivalent buffer_[append|copy]_string. So lighty must run strlen() to determine the size of a string where the lenght is already known. To check the length of only a "." (point) the loop inside strlen() ends very quickly. But lighty has some places where this "problem" is more critical - for example to combine HTML-components in connections.c.
Update:
The patch was included in thecurrent release 1.4.20!