Outlook 2007 Performance Troubleshooting Checklist

Outlook performance cases and issues can be one of the more difficult items to troubleshoot when dealing with messaging. In some cases it can be isolated to one item like physical performance issues on the Exchange server or potentially a 3rd party add-in which often happens. The most important thing to consider is that it is possible that is an amalgamation of many different things or different portions of the client to server Path which would encompass the following:


As mentioned above we need to look at how the round trip of the MAPI request takes to complete the full circle from the Outlook client, through the network, and fetched off the server. Looking at just the client portion of this trifecta we can help alleviate some of the “performance pain” which is all based on the following article “How to troubleshoot performance issues in Outlook 2007”, *http://support.microsoft.com/?kbid=940226. The main focus and overall recommendation for an Outlook clients is to have the client in what is called cached mode. There are many benefits of having you mail locally “cached” and like portable mail access, independency of network connectivity, local search and indexing, less burden to shared mail servers, and potential increased storage on the backend assuming less expensive disks are used on Exchange.

While not all users may conform to these 100%, it is important to understand that we should expect delays if we can’t hold to some of the known limitations if the user insists to be in “online” because of a misconceptions that cached mode is bad which may not be the case. Below are some of these common items to consider that are considered potential issues with cached mode”

1. Reduce Non-Default COM Addis: Outlook 2007 has the capability to have add ins that literally hook into Outlook to connect to the mail system. These can range from Anti-Virus plug ins, business applications (e.g. Interwoven), and data sharing applications. These add ins can cause huge performance hits against a workstation when loading and using Outlook. We starting to look at performance issues make sure to unload all non Outlook adds under COM adding and Exchange Client Extension found under tools, Trust Center, Add ins. Below is the list of the Microsoft shipped default addins:

COM add-ins
Microsoft Access Outlook Add-in for Data Collection and Publishing
Microsoft Exchange Unified Messaging
Microsoft Office Groove Proxy for Outlook Add-in
Microsoft Office SharePoint Server Colleague Import Add-in
Microsoft Office Outlook Mobile Service
Microsoft VBA for Outlook Add-in
OneNote Notes about Outlook Items
Windows Search E-mail Indexer
Exchange Client Extensions
Delegate Access
Deleted Item Recovery
Exchange Extensions commands
Exchange Extensions property pages

2. Have Outlook SP2 or greater: Build 12.0.6423 of Outlook 2007 incorporated major performance improvements in the product. Having a lower version will have a detrimental effect on how many items per folder and size of the OST files
3. Have less than 15,000 items: In any folder, especially the inbox, the item count is recommended to be below 15,000 assuming the client is using Outlook SP2 build as mentioned in recommendation 1. This can also be a problem with Outlook 2007 in online mode (non cached) since we have to deal with physically building this view on the Exchange server and transmitting the results via RPC back to the client. Have custom (non-default) views in addition to large item counts can aggravate the slowness even more.
4. Have less than 5GB OST file: The new build of Outlook SP2 (12.0.6423 or greater) busted through the performance barrier with OST files which was limited to 2GB originally. The newer version of Outlook 2007 you can expect the following as outlined in the “How to troubleshoot performance issues in Outlook 2007” article:

• 25GB: This size increases the frequency of the short pauses, especially while you are downloading new e-mail. As described above, you can use Send/Receive groups to manually sync your mail.

5. Use Very Fast local Hard Drive: Since Outlook 2007 in cache mode will store the OST have a fast drive that is not over burden with other I/O from other applications or system process (e.g. background Anti-virus and/or defragmentation tools) is absolutely critical for best user experience. If slower 5400rpm or Solid State Drive (pre September 2008) that perform less than 40MB/sec are in workstations the expected performance with Outlook 2007 will be poor.
6. Use Folder Synchronization Filters: By default the Offline Folders in Outlook will synchronize every item in every folder regardless to whether or not the user will truly needed it. You can within outlook make certain messages become “hidden” and unavailable to be download but they still exist on the server. The downside to this is that the user will not be able to see if the message is actually there or not unless the user removed the filter in Outlook 2007 cached mode, go to Outlook 2007 online mode, or use Outlook Web Access. For more information on this please see
7. Limit the amount of custom Views: The default views in Outlook will work best for view and rendering items quicker. We recommend using “Arranged By: Date” because as mentioned any other view will add to the overhead and create a potential “slow” Outlook 2007 experience. One thing that a user can try is to see if any views have become corrupted that can cause severe performance problems in which I have seen Outlook 2007 slow cases become solved by using this switch. This can be corrected by using running outlook in the run command line with the syntax “outlook.exe /cleanviews”. To get a good understanding of views and even associated item count please look at the article, “Understanding the Performance Impact of High Item Counts and Restricted Views” found at *http://technet.microsoft.com/en-us/library/cc535025(EXCHG.80).aspx
8. Limit amount of open mailboxes: In outlook the user has the ability to add multiple mailboxes to load on startup. This will always increase the load time as you are literally connecting and logging onto an alternate mailbox, potentially even on another Exchange server that may or may not be experiencing performance issues.
9. Verify that PST Null Free on Close does not Exist: If there was an Outlook client that was upgraded from a previous build (pre-Outlook 2007 SP2). We have found issues that if the following key exists and is set to 1
Key: HKEY_CURRENT_USERSoftwareMicrosoftOffice12.0OutlookPST
DWORD: PstNullFreeOnClose (needs to be at 0, not 1)
10. Clean out Calendar Stubs: Over time the use of Outlook will remember which shared calendars that you may have opened up in the past. Having these still present, especially if the user no longer exist in the organization, can cause a slight delay when switching from mail to Calendars (usually after around 20 minutes). One item that has helped out a lot is to clear out the shared calendar stubs by using the “outlook.exe /cleansharing” command from the run command. For more information on this switch and many others that are available please see the following:
11. Uncheck Outlook integration if presence is not needed in Outlook: Outlook 2007 can interfaces with OCS (Office Communicator Server) for presence information. This can be disabled so that outlook will not attempt to search for a server and user presence to prevent unnecessary delays. In order to disable this feature, click on Options on the Tools menu and then unchecked the box next to “Display online status next to a person name check box under Person Names”


About Joe Trombley (MSFT)

Got a question about Exchange and want to ping it off a Microsoft Certified Master that works for Microsoft as a Senior Premier Field Engineer or just recieve some good information about Exchange? This is the place. Join today! I am here for you.
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