Many open shared calendars slow Outlook performance

[MichaelMuha]

This is mainly an informational post, not a request for help...

Whenever Outlook sends/receives, it syncs e-mail and all open calendars. Some of our users have 25-40 calendars, shared from others, open simultaneously. If Outlook syncs every 5 minutes, all those calendars sync as well. This kills Outlook performance because Outlook is constantly syncing.

Those users are now instructed to keep shared calendars open in the web client and to use Outlook for mail and personal calendaring.

(Of course, you may ask "Why do they need to have a zillion calendars open at the same time?" Usually, it's a power user in charge of juggling to few conference rooms.)

A possible enhancement for Zimbra would be to only sync calendars when Outlook has the calendar in a view...

Mike

[alee]

Originally Posted by MichaelMuha

This is mainly an informational post, not a request for help...

Whenever Outlook sends/receives, it syncs e-mail and all open calendars. Some of our users have 25-40 calendars, shared from others, open simultaneously. If Outlook syncs every 5 minutes, all those calendars sync as well. This kills Outlook performance because Outlook is constantly syncing.

Those users are now instructed to keep shared calendars open in the web client and to use Outlook for mail and personal calendaring.

(Of course, you may ask "Why do they need to have a zillion calendars open at the same time?" Usually, it's a power user in charge of juggling to few conference rooms.)

A possible enhancement for Zimbra would be to only sync calendars when Outlook has the calendar in a view...

Mike

some of the performance problems that you are seeing might have nothing to do with ZCO syncing but just normal Outlook behaviour. there is a memory overhead with mounting a PST to an existing Outlook profile. we were seeing this at around 15-20MB per mounted PST (shared calendar). so if you are mounting 40 shared calendars, you could be talking about an outlook process in the neighborhood of 800MB which could be killing performance and could make it seem like outlook is always syncing. I'm assuming that you are using Outlook 2003...this memory problem seems much smaller with Outlook 2007.

[rduric]

Lots of my users are using Outlook 2007 (ZCO 5.0.7) and still experiencing the same problem. If someone sends a request for a meeting and invite a larger number of people and if a few of these invitees share calendar with me, my Outlook stops receiving email, my BlackBerry on ZCB Beta 3 also stops receiving email. The Zimbra Send/Receive progress shows that one of my shared calendaring is processing. In the last few days this happened two times and I needed to wait around 3 hours until I received all messages at once in both the BlackBerry and Outlook. During this time I would be receiving emails in ZWC. This problem would affect both Outlook users with and without BlackBerries.

[alee]

Originally Posted by rduric

Lots of my users are using Outlook 2007 (ZCO 5.0.7) and still experiencing the same problem. If someone sends a request for a meeting and invite a larger number of people and if a few of these invitees share calendar with me, my Outlook stops receiving email, my BlackBerry on ZCB Beta 3 also stops receiving email. The Zimbra Send/Receive progress shows that one of my shared calendaring is processing. In the last few days this happened two times and I needed to wait around 3 hours until I received all messages at once in both the BlackBerry and Outlook. During this time I would be receiving emails in ZWC. This problem would affect both Outlook users with and without BlackBerries.

can you enable ZCO logging to see what ZCO is doing in that 3 hour period?
ZCB logs could do it too.

[snissen]

There may be another way to help this problem: Outlook allows you to create Send/Receive (S/R) groups with different synchronization schedules. Leave a person's E-mail and calendar in the default S/R group with a short refresh (5 min), and then put all the shared calendars in a new S/R group with a longer sync schedule, like 30 minutes.

I don't know for sure this would work, but it seemed to help me. Sande

[rduric]

I am not sure how to set this up since I have only one group (All accounts). The shared calendars I have belong to this group as well and I don't see any configuration option in case I have only one account.

Most likely I'm hitting this bug: Bug 30991 – ZCO takes a long time to load an ics with lots of attendees

We had imported Oracle calendar into Zimbra and are now experiencing serious challenges. The ZCO clients are particularly hit hard...