Painfully slow sync w/ CalenMob

[iMore Question]

CalenMob Pro on iPhone 4 w/ ios7
The sync takes 20 minutes or more and even at that will revert to the home screen at the end without completing a successful sync. Even startup of CalenMob can take 60 seconds. I upgraded to Pro thinking that might help, but no difference. A calendar that doesn't sync is not of any use. Help?!

 

[iEd]

You may want to contact the developer on iPhone 4 and iOS 7 compatibility. Based on the reviews I've read iOS 7 compatibility was fixed in the last update.