Extremely slow load on calendar and loads of 404s

I’d love to keep running all-in-one but it is extremely slow to load on my site (www.mudstacle.com/events). Any ideas why?

Also I’m getting literally hundreds of 404s being reported. I can send a full report, but most of them look like this:

webcal://www.mudstacle.com/%3Fplugin=all-in-one-eventcalendar&
controller=ai1ec_exporter_controller&action=export_events&cb=1102313374

webcal://www.mudstacle.com/%3Fplugin=all-in-one-eventcalendar&
controller=ai1ec_exporter_controller&action=export_events&cb=1108962667&ai1ec_cat_ids=3
0

webcal://www.mudstacle.com/%3Fplugin=all-in-one-eventcalendar&
controller=ai1ec_exporter_controller&action=export_events&cb=1111302310

Any ideas why that’s happening?

http://wordpress.org/plugins/all-in-one-event-calendar/