Developing applications under Cyanogenmod? How compatible to vanila Android? (Nexus devices)
The governor is dependent on the OEM's choice. For example, some choose mpdecision, others use ondemand or interactive. Still others use conservative. That being said, many of them are implemented differently (ie conservative mode on a Samsung may differ wildly from conservative on an HTC). Cyanogenmod though is just based on AOSP code so ondemand/interactive governor performance under Cyanogenmod should be comparable to the stock governors for that device (OEM's implementation).  This is assuming that the Cyanogenmod branch for said device has proper hardware acceleration and what not. As Cyanogenmod is built from AOSP code, this is not a given.

TLDR: I have had a lot of phones with Cyanogenmod. It feels snappier and is lightweight but for the heavy duty apps or games, I notice very little (if any) difference in performance.