Why does when Web Crossing become unresponsive/performance suffers when I do a backup with repack?

NOTE: Upgrading to any v4.1 after 10/25/01 will contain changes that optimize repack performance to the point where the impact on the site is generally minimal.

There are several steps to a backup with repack, and it is time consuming:

* make a copy of all the objects in the original database, packing them up
so as to remove all fragmentation, and keeping track of old/new object
handles
* make a pass over the packed-up DB to update all object handle references
from the old handle to the new one. This can take a long time.
* make a pass over the packed-up DB to check all DB segment-list
structures (used for each folder, the member directory, highwater marks,
etc. This can also take a long time.
* finally, save all the webx.db changes to disk and switch to the repacked DB.