Apache attacked by a "slow loris"

You can't lower the stack sizes. One of the biggest reasons that Apache administrators have to keep with older Apache MPMs is for crap like the mod_php, which is likely going to crash with lower stack sizes.

Honestly, if at the end of the day you don't need any of the Apache modules (maybe you're using regular CGI or fast-CGI or something), then just don't use Apache, but instead use one of the newer, more efficient, more scalable Open web servers, like lighttpd, cherokee, etc.

(Unfortunately, the lack of .htaccess support in those servers, and hence the lack of mod_rewrite-compatible user-configurable rewrites and redirects, is a real issue for a lot of hosts. If those servers added an optional module for basic .htaccess-like support, they'd probably skyrocket in adoption.)