Well as it is a prerelease I cannot really blame Jolla for it.
When it is released for everybody then I agree thing like that should not happen.

One thing what I have noticed is that some operations are notably slower after enabling device encryption; for example device unlocking after typing the code takes about 2 seconds compared to almost instantaneous unlock of an unencrypted device. Also checking email takes about 30 seconds agains about 10 seconds before.