Importing a 1000 event calendar into Chandler I get the following times.

Attribute Timed	Linux QA Machine Build: Checkpoint 20050613	Anthony's Mac Laptop Build: Checkpoint 20050613	Windows QA Machine Build: Checkpoint 20050613
Importing calendar	39 seconds	86 seconds	33 seconds
Switching from All view to Calendar view	5 seconds	6 seconds	3 seconds
Switching from Calendar view to All view	2 seconds	4 seconds	2 seconds
Creating a new event	0.9 seconds	2 seconds	0.7 seconds
Stamping event as email	2 seconds	3.6 seconds	1.5 seconds
Moving event in Calendar view	0.8 seconds	1.2 seconds	0.7 seconds

Here is a comparison with other calendar programs:

1: The Outlook calendar was exported as a Personal Folder File (.pst)