I think the forest level may not be 100% smooth all the time, although the space level pretty much is. But both run very well and are really playable.

Running something on the background will affect this of course, but without reboot or without turning off phone but just not running anything else seems very playable to me. It is perfectly OK while playing music on the background too.

For those still looking for those hidden apples... read this in reverse:

seert eht kcik