[kronolith] webdav ics performance issues

[Elliot Anders]

We're getting tons of complaints about the performance of Sunbird and  
the webdav ics provider. We realize that this is somewhat related to  
Sunbird's slowness of calendar display and it's inability to reload  
remote calendars in the background, but have also seen horde/kronolith  
respond extremely slowly with the requested file.

I'm hoping to do some investigation as to where the slowness is (RAM  
on the machine doesn't seem to be and issue, CPU usage is minimal  
throughout the entire process, and mysql doesn't seem to be the  
bottleneck either.)

I'm thinking it's probably related to the creation and parsing of ics  
files as the delay increases with greater number of events.  We're  
seeing a 10-20 second delay on a calendar with ~200 events.

Has anyone else already investigated this and found solutions?  I know  
Iikku recently asked about  the XML-RPC being slow, and the response  
was basically that importing was treated as a one-off event (totally  
acceptable in my opinion.)  Does the webdav iCalendar parser have the  
same issue? I'm going to guess it does, which seems like it might be a  
fairly large issue pending the release of a caldav implementation.

I'll report back with my findings, but if anyone has already poked,  
please let me know.
-Elliot