If anything was learned about dual-core phones with the HTC EVO 3D, it’s that turning the second CPU core on only when needed produces a jerky, slow phone. When the EVO 4G LTE was released, I assumed the on-demand second core concept would have been a thing of the past but evidently not. Thankfully Viperboy has released a dual-core mod to remedy that oversight.
The theory behind how the cores are controlled by default is that keeping the second core off until such time as it’s needed saves battery power by not requiring juice to the second core. In practice what happens is a short delay as the second CPU comes online which results in longer execution time and more overhead. Keeping the second core on and idling means it’s on and ready when you need it and can be tasked for any processes that need it. This can result in lower execution times/less screen on time/power savings.
Users are reporting slightly snappier phones with no huge increases on either performance or battery drain. As always, your mileage may vary depending on usage.
If you’re going to try this, make sure to make a Nandroid backup beforehand, and let us know how it works for you.[xda-developers]