I cant imagine that Airtime is really that slow, but that something is wrong. Some observations:
Airtime 2.3.0
1. Airtime is running on a freshly install Wheezy on a virtual machine on Virtualbox
2. Total free ram is 600 MB
3. I can not save any settings on /Preferences - if I click on Save, nothing happens.
4. Aftert some actions Airtime seems to hang. If I restart Apache2 it works again.
5. I have scanned all logs and did not find a hint for any error.
6. It was installed via the DEB file linked on http://en.flossmanuals.net/airtime-en-2-3/easy-setup/ . I got one error that /usr/share/airtime/debconf-selections could niot be found after this package was not quite fully installed.
7. Anything else looked good. I could upoload files and also play them.