Why is MAMP PRO so slow?

Not sure. But I can tell you how to fix it.

Run the following series of commands:

# Where yoursite.local is the name of your site
sudo echo '::1 yoursite.local' > /tmp/newfile
sudo cat /etc/hosts >> /tmp/newfile
sudo mv /tmp/newfile /etc/hosts

Problem solved! Check it out for yourself at yoursite.local right now.

Cheers!