Why Outlook 2007 is slow: Microsoft’s official answer

A knowledgebase article published last week acknowledges performance problems with Outlook 2007, though it says these only occur with mailboxes larger than 2GB:

You may experience one or more of the following performance problems when you are working with items in a large Personal Folder file (.pst) or in a large Offline Folder file (.ost) in Microsoft Office Outlook 2007 … Note When you perform the same operations on the large .pst or .ost file in earlier versions of Outlook, the same performance problems do not occur. These problems may occur if the .pst or .ost file is larger than 2 GB. Additionally, the performance problems are more pronounced when the .pst or .ost file is larger than 4 GB.

I think this is optimistic and that smaller mailboxes are slower too; nevertheless, it does confirm that that the size of the local store is the key issue.

If you use Exchange, the local store is the .PST or .OST file on your workstation or laptop. If you do not use Exchange, a local .PST store is all you have.

Here’s what Microsoft says is the reason:

To accommodate new features, Outlook 2007 introduced a new data structure for .pst and .ost files. In this new data structure, the frequency of writing data to the hard disk increases as the number of items in the .pst or .ost files increases.

Intriguing, especially as I had thought the .pst format was the same in Outlook 2003 and 2007. The big change was from Outlook 2000 to Outlook 2003, when Unicode was introduced and the maximum size increased to 20GB.

I’d also like to know whether Microsoft is just stating the obvious here (bigger file, more disk access); or whether there is some exponential increase in disk writes, suggesting a design fault in the software. I have already noticed that if you show the I/O columns in Task Manager’s performance tab, Outlook 2007 shows some extraordinarily large numbers.

So what’s the fix? The news is not too good. In essence, you have to reduce the size of the local store. You can archive or move items to separate .pst files, or switch off cached mode so you always work online to Exchange.

The article doesn’t say it, but there are significant problems with switching off cached mode. These include hugely increased network traffic, problems with junk mail filtering, and loss of all your mail when using a laptop disconnected from the network.

The most imaginative suggestion is to filter the sychronization. For example, you could filter out messagse with large attachments, or all messages from last year or earlier. These messages will still exist in Exchange, but not in the local store.

Worth a try, but none of the workarounds is really satisfactory. Outlook 2003 worked fine with large mailboxes, Outlook 2007 does not. That’s a blunder.

 

158 thoughts on “Why Outlook 2007 is slow: Microsoft’s official answer”

  1. Yeah, the most obvious solution is to go back to Outlook 2003.

    Incidentally, as an aside, how do you get Word 2007 to display the name of the current style (where the carat is)? In Word 2003, the dropdown list of styles on the toolbar automatically updates, but in Wood 2007, the ribbon’s style chooser doesn’t seem to. It’s really annoying and I’m this close (–>

  2. > Incidentally, as an aside, how do you get
    > Word 2007 to display the name of the current
    > style (where the carat is)?

    Alt-Ctrl-Shift-S shows the styles window which does this.

    I have it on the quick access toolbar.

    Tim

  3. One very annoying thing that Outlook 2007 does is, if you use IE7 and use the RSS feeds, Outlook will import the RSS feeds and keep the items indefinitely, unlike IE7 which observes feed limite.

    My XP box running Outlook 2007 beta went from a “normal” PST size of 300M to 1.6G (!!!)

    Turn this off: Go to Tools/Options/Other/Advanced. Uncheck “Sync RSS Feeds to the Common Feed List” and “Any RSS Feed that is updated appears as a new item”. Click OK three times. Then go to Tools/Account Settings/RSS Feeds. Select all the items there and click Remove.

    Then have fun deleting all the feeds already downloaded. You *will* croak Outlook if you try to delete them all at once. I had to delete just a few items at a time and I probably still migrated some junk to to my Vista install.

    The Outlook resource management process seems to be at O(n*2) performance. Sigh.
    Take care,
    Dave

  4. > One very annoying thing that Outlook 2007 does is, if you use IE7
    > and use the RSS feeds, Outlook will import the RSS feeds and
    > keep the items indefinitely
    Don’t get me started! Outlook’s RSS implementation is tragically broken. See also http://www.itwriting.com/blog/?p=54

  5. I am using ONLY POP3 accounts with Outlook 2007 and the send/receive process is ungodly slow for me as well. I have been download 4.05MB of emails this morning for over 20 minutes already, and just hitting 3.8MB.

    This is an issue that MS should address NOW.

  6. The performance issues are down to PST filesizes. My trials reveal that any PST file above 600MB causes massive performance problems. The smaller you can make those PSTs, the faster it will work.

    This is a massive shot in the foot by Microsoft. Outlook 2007 is fundamentally broken due to bad software design choices.

  7. This is a bug, right? “Performance issue” just doesn’t do it justice. Outlook 2003 broke the 2GB barrier on pst sizes, which was a welcome thing for me because under Outlook 2003 my pst grew to 3GB. Now we have this new improved program that needs mailbox sizes to stay under 600 MB? MSFT needs to issue a hotfix for this bug now.

    Ever since I’ve installed 2007 I haven’t been able to open my pst file. As a workaround I’m going to use a laptop running 2003 to break the pst into multiple psts, but I don’t view this as solving the issue.

  8. I feel your pain. I have attempted to run outlook 2007 on a newly purchased Dell notebook running Vista. The performance was simply so bad that it was not viable. So… I have uninstalled and installed outlook 2003… and… the performance is almost as bad.

    This is 1.8GHZ Core Duo with a 4MB cache and 2GB of RAM. Outlook is continually using 80-90% of one core, dropping down to 0-20% every 8 or so seconds for a fraction of a second then straight back up again. Memory usage seems to continually track up into the 100’s of MBs even when doing nothing.

    I too had a large mail box (1.7GB) but have trimmed it to under 800MB, but really this is crazy!

    Has anybody tried outlook 2003 running on Vista and experienced similar issues?

  9. After many hours of investigation (and using the Vista Reliability & Performance Monitor) I have found the culprit for my Outlook 2003 performance problems on the Dell Notebook. The dell MediaDirect component was causing all the grief. Uninstalled and all is OK!

  10. I have upgraded from Office Pro 2003 & Outlook 2003 to 2007 from within MS Office Pro 2007. (1) Many email messages are returned with a note telling me to use SMTP address format. How can I do that? (2) I also know that some messages are not getting to me and some of mine are not getting to the person I’ve sent them to. (3) One person has told me he cannot read the messages I’ve sent him. Suggestions & advise please. Tom VC+

  11. Just bought a Compaq Presario running Vista.

    It’s loaded up with Outlook 2002, from the installation CD that came with my SPV C600 smart phone.

    On my old desktop running XP, I synced my phone using ActiveSync. On Vista I’ve had to download Windows Mobile Device Center… problems:

    1. Smart phone will not sync with Outlook.

    2. Everytime Outlook is launched it asks me for a network password, in spite of me entering this in Email Accounts and checking the save password box.

    3. Everytime I click Send and Recieve I get an error message telling me to check the spelling of my email address in Email Accounts – which is correct.

    Annoying? Doesn’t even come close. I call up PC World for help. They tell me to buy Vista Outlook 2007. I look it up on the net and discover (here) that it takes ages to download mail and I don’t want to go from the pan into the fire.

    So, I am stuck with obselete Outlook and no prospect of sorting it out. The answer? Well, I guess to strip Vista off my laptop and get XP loaded up. And make sure that anyone I know buying a new laptop goes for a Mac, since within a matter of weeks XP will no longer be available as na OS on a new system.

    If anyone can help with the issues above I’d appreciate it!

    Cheers – Sean.

  12. microsoft 2007! what a nightmare…nothing but constant not responding errors all in outlook.

    the latest issue however is that some contacts are receiving me emails but others are not…??

    any ideas ???????

  13. So microsoft thinks people’s email folders are getting smaller? They really have their head up their ass in Readmond.

  14. Sara,
    Tell your recipients to add YOUR email address to their “Safe Senders List.” They are more than likely getting your emails but it is going in their Junk Mail folder rather than their Inbox. Another suggestion would be to have them check their firewall settings. It may be blocking certain types of email msgs coming in.

  15. I have a new Dell XPS M1210 running XP and Office 2007. My PST is only 90MB. Outlook was very slow and intermittently unresponsive. I followed the tip to uninstall Dell Media Direct – so far it works a treat! Thanks

  16. I recommend most users should stick with Windows XP and Office 2003 for a couple more years until one or even two service packs are released.

  17. CAN’T WAIT FOR A FIX! I’m going to move to another program for my e-mail. Outlook 2003 was barely acceptable, 2007 is just useless.
    I’m using Outlook 2007 for 7 different POP3 accounts. It’s so slow downloading that I can’t get anything done.
    When it’s checking the mail, Outlook basically stops. I can’t do anything except during the 1 or 2 minutes while it’s not downloading mail.
    I’ve got a fast new Core Duo system with 3gb ram. And yes, I have a Big PST file, about 5.2gb – But before I switched from Outlook Express a couple of years ago to Outlook, I’d had 10gb archived and had no problems at all. I switched to Outlook so I could use a Blackberry, but now I’m going to rethink the whole strategy.
    I have a large number of IT clients that don’t find “reducing the size of their mail” an acceptable solution. I can’t understand why Microsoft can’t make an e-mail client that actually works.
    Anybody had any recommendations on an E-mail client that handles large amounts of archived e-mails?

  18. Tim, I Googled “Outlook 2007 slow” and got a hit on your blog. I have been struggling with Outlook 2007 on Vistg Ultimate for about six weeks. Outlook is a dog – but, my PST is only about 700K. I’ve got two POP accounts and two Windows Live accounts (using Outlook Connect) configured in this profile. If I click on a blank calendar item to create an appointment I get the blue spinning circle for 10-20 seconds. It’s absurd! Any other ideas as to cause if the problem isn’t a large PST?

  19. Susan,

    If your PST is small then there is hope. There are numerous possible solutions which have been posted here (see the other threads too), most of which involve disabling add-ins.

    Tim

  20. Outlook 2007 is has killed my productivity. I think that the issue is also related to it trying to sync to Sharepoint. In playing with sharepoint 2007 I sent an alert out, click on sync tasks and boom! my email gets blown out. I’ve deleted my OST, uninstalled, reinstalled, run in cached mode, not in cached mode… the only way that I can be semi productive is NOT to use cached mode. Makes it impossible to travel with my laptop.

    I’ve had to delete all of my RSS feeds, but every time I boot up outlook it goes back out and finds my sharepoint sites and starts downloading information (while outlook.exe is taking up 99.5% of my cpu)

    I’ve been non-productive for 2 weeks and am about to throw it out the window. I’m going a MS CIO forum in Redmond in May – I was going to skip it this year, but I need to give them a piece of my mind.

  21. Okay – after readying the other thread… I disabled all of the add-ins. At least now I can get into outlook with out it jumpint to max cpu utilization. I disabled all of the add in’s.

    Still have the dang thing going out and pulling info from sharepoint.

  22. Hi Tim, I’m experiencing slow alt-tab screen changes in Word 2007. Any idea what might be the reason? It basically takes about 1-2 seconds before it switches the screen.

  23. Hi Tim,

    I’d like to share my personal experience with this bug (or a related bug). Since I have installed Outlook 2007, I’m also experiencing slowness problems and regular (that is, 2 or 3 times a day) crashes while typing in messages. However, this occurs only on my dual core system. While typing in a new message, the caret suddenly disappears, Outlook grabs 100 per cent of one CPU and locks up.

    My .pst file is “just” as big as 259 MB, though. And I have no .ost file. I have 3 workstations on the network using Outlook 2007. One system is a dual core and the two others are monoprocessor systems. However, they use an identical .pst file. They do not
    share the same pst file but it is identical on all systems because I’m using a synchronization tool. So if the problem was related to the size of the PST file, it should occur on all systems, which is not the case. This is why I think it’s a thread synchronization issue. It’s the kind of bug that very often only appear on a dual core or multiprocessor system because only in those cases there is really simultaneous execution of multiple threads.

    I have submitted an MVP feedback about this issue.


    Patrick Philippot – Microsoft MVP (Dev)
    MainSoft Consulting Services
    http://www.mainsoft.fr

  24. Thanks Patrick. One of the reasons this “slowness” issue is hard to nail is that there seem to be multiple causes. For example, I have a dual core laptop, but I don’t see the symptoms you mention (caret disappearing, crashing) even though I do see slow performance. I have a much larger OST.

    Could this be add-in related?

    Tim

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