I recently read an article about how you can install HipHp Virtual Machine (HHVM) for a 2x+ speed boost on your site. The newest version of WordPress works 100% with HHVM, but unfortunately some of the plugins out there don’t. I decided the pros out weighed the cons and decided to install HHVM on my development server. Outlined below are the steps for installing it on your own.
wget -O - http://dl.hhvm.com/conf/hhvm.gpg.key | sudo apt-key add -
echo deb http://dl.hhvm.com/ubuntu saucy main | sudo tee /etc/apt/sources.list.d/hhvm.list
sudo apt-get update
sudo apt-get install hhvm
sudo update-rc.d hhvm defaults
sudo /etc/init.d/hhvm restart
sudo /usr/bin/update-alternatives --install /usr/bin/php php /usr/bin/hhvm 60