These are my enabled mods:
alias
auth_basic
authz_default
authz_groupfile
authz_host
authz_user
autoindex
deflate
dir
env
mime
negotiation
php5
reqtimeout
rewrite
setenvif
status
I'm attempting to reduce Apache's memory footprint as much as possible.
Can anyone guide me in the right direction as to which of these I absolutely need and which are optional? I plan on running Symfony, but I couldn't find any requirements about symfony to get it all working.
Well, you can start by disabling all auth / authz modules, unless you're going to have Apache do authentication work for you, in which case only enable the auth module that you're actually going to use.
You may not really need the autoindex module; you only need it if you'd like Apache to generate index files automatically.
deflate — you actually want that, so Apache can gzip-compress data before sending back to the client (dramatically reduces traffic).
reqtimeout — that's experimental. Not sure if you included it intentionally or not.