This is a known problem, VSync is forced on in Freelancer regardless of driver settings. And it's an issue because it causes severe mouselag. Most people recomment the ATI Tray Tools to workaround this issue, but it's limited: Once you ALT+TAB out of Freelancer, FPS are locked again.
I want to gravedig this, because I found a program that completely solves this issue even better than ATI Tray Tools.
The problem that fixes this issue is called "RadeonPro": http://www.radeonpro.info/en-US/Downloads/
Install it, add the Freelancer.exe (the Disco one) to the list, go to advanced settings, tick "agressive API detection" and force VSync off.
Now you can play Freelancer without mouselag and even with ALT+Tabbing.
