I've always wanted to play with putting /var/www into a ramdisk for PHP/html stuff. Would be much faster loading since it's all just text in the end of the day. Completely cut out the bottleneck of SSd/HDD
It might help with latency for the long-tail of data that isn't used very often and thus maybe replaced in the cache by other data, but on the other hand the OS probably had a reason to replace it and forcing it to stay in RAM might slow everything down.
I could be wrong.