Yeah lag is an issue with older devices but cocoonjs has released a new version with speed improvements that I will load up soon.
And taking your finger off the screen momentarily although seems an easy way to survive, it is often the cause of confusion, as in, if you keep your finger on the screen the cubes can be organised like zombies on Call of Duty.
I don't want a severe penalty for it but maybe lifting your finger initiates the rainbow circles to begin their fade animation?
Thanks for the feedback!