If your game depends on timing, your frame rendering loop should use timers to control the frame rate.
Our simple2d sample application just renders frames as fast as it can and you do see a difference in game timing between the Roku1 and Roku2. You could add a wait() in that loop with a timeout that you calculate to be the next frame rendering time.
Of course, it's possible that the Roku1 will not be able to support the frame rates that the Roku 2 does but your timers in the render loop should keep the timing of your game the same on both platforms.
I looked into the wait() inaccuracy on the Roku 2, and unfortunately we have had an open bug on this platform that affects both wait() and sleep(). Enabling the high resolution timer in these methods caused instability in the firmware so it is currently disabled. We'll have to fix these before using wait() or sleep() becomes a viable option for this use case.
In the meantime, you could use the rotimespan component to get a high resolution timer and check for events in the busy-wait loop with a call to msgport.getmessage() (which does return immediately whether there's a message or not).