While running on a server, selecting a page with a complexDataField or CalendarDateField in the CMS takes a long time to load. Pages without these fields loads normally.

Commenting out the Require::javascript inside the core field classes causes the pages to run normally, but makes the fields un-editable. We suspect it's how the CMS includes the js files dynamically, and would like to make a bug ticket if it's the problem.

For some weird reason the performance is normal if it's running locally, or on a different network. So it might be a ISP issue.

This issue does not effect silverstripe 2.2

That was one of my main objectives in creating DataObjectManager. That popup window is all together too slow, and if you look at the amount of Javascript overhead you're dealing with, it's no wonder.

You should try DataObjectManager instead. It comes with its own calendar date picker that is jQuery based and a lot slicker if you ask me.

Great job, and I love the new datepicker! Would it be possible to maybe add an option to clear the datefield as well?