I have a fix for non-developers on FRX04 that should improve both application performance and compatibility. tiad8's builds already contain this improvement. I'm not sure whether things were setup originally in FRX04 this way intentionally to help with development, but if the setup was not intentional, then it'd also be good if someone could bring this to the attention of the relevant developers to change for the next version of FRX04.
Stock FRX04 shows incompatibility with certain programs, notably, everyone's favorite Angry Birds Lite is a good example. This is easy to verify, just download and install and verify that it crashes to home screen. Available here:
Angry Birds Lite Beta - Android app on AppBrain
This is caused by this line in the build.prop file:
ro.kernel.android.checkjni=1
According to documentation, enabling this option "will cause the system to run more slowly" as it runs more checks for properly written code, which can help developers to "spot a variety of nasty bugs before they have a chance to cause problems". Since most users aren't developers and aren't using this feature, disabling this makes sense.
Change the line to =0, and application compatibility is improved. Reopen your favorite non-working app, such as Angry Birds Lite, and bask in the warm glow of your screen as your app starts (assuming it is one of the affected apps).
I have attached modified versions of the relevant files if you want to install the fix but don't want to modify your build.prop inside system.ext2. Just copy froyo.user.conf into your conf directory over any existing version, and copy build.prop into the root directory of your SD card (not your andboot directory).