Once upon a time, the FOSS developers used to create "one program for one task only, which does it well".
Here is what I reported at Ubuntu:
https://bugs.launchpad.net/ubuntu/+bug/1000265I have done the same at Mozilla some time before, but there I received a bad return for asking to restart a program which was obsoleted.
Calendars, Address books, all are included in mail suites, but having them separately is good for the resources, for we don't always need to have them all started at same time, and we can choose the one items we prefer. Instead of that, I had to replace Contacts and Sunbird by Evolution which has been the only program able to import the exports from the dying Contacts and Sunbird, but I have never used the mail from it, Sylpheed being the one for many years yet.
Evolution is also quite long to be started, even in the desktop with 4Gb ram and and dual-core amd athlon with enough "muscles".
Let's wait and see how will be the new gnome-calender mentioned by jbisha in the thread:
http://erick2red.github.io/blog/2013/06/25/june-update-on-calendar