Hello EM Client Team. I am running icloud calender on em-client. It would sync, but only after many minutes. For example: when I change some Appointment on my calender on my PC via em-client, my Mac will show the cange instantly. the other way around, when I change an Appointment on my Mac, it takes many minutes till em-client will do the right changes on my PC. Only when I press the “refresh” button, then changes will show up… PLEASE HELP FOR STRAIGHT PUSH-FUNCTION!!!
You can change the sync interval in Menu > Tools > Settings > General > Synchronization, to 1 minute. That is the best you can get. 
This setting affects only calendars, contacts and POP email.
Of course, creating or changing an event in eM Client is always immediately updated to the server.