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