I am using Microsoft Outlook 2007 to access my official mails. Lately I have seen that Outlook takes a long time load, sometimes greater than 2 minutes. The outlook folder size is also not much (around 250 MB). Rest all applications, including Visual Studio 2010 load quickly and are behaving as they should. Why is Outlook slow?

OS - Windows 7 Ultimate Edition (x64), 4 GB RAM, 500 GB HDD


Some steps that are reported as helpful :

  1. Turn off indexing on particular hard disk drive
  2. Run Outlook as Administrator
  3. Control Panel -> Mail, "Data Files" button, "Data Files" Tab, ensure that your .pst is not mentioned.
  4. With Outlook closed, rename C:\Users\<username>\AppData\Local\Microsoft\Outlook\extend.dat to extend.old.

Microsoft says :

  1. Reduce the size of the Exchange mailbox
  2. Use an online mode profile instead of a cached mode profile
  3. Split your large .pst file into several smaller .pst files
  4. Use a filter to restrict the items that you synchronize from Exchange to your .ost file

More stuff from Microsoft Outlook 2007 Running Slow :

  1. Disable RSS Feeds
  2. Disable Outlook Add-Ins
  3. Start Outlook 2007 in Safe Mode and see if this is faster

Some more advice can be found in How to Speed Up Outlook 2007.

  • 1
    Apparently Outlook Hotmail Connector was somehow installed which was slowing things down. – Mayank Dec 10 '10 at 19:12

How many emails do you have, and do you use IMAP at all? Outlook has know issues with IMAP and can be slow if you have more than 5,000 emails.

  • My Inbox+Sent with all the sub-folders included contain around 1500 mails. I am using Microsoft Exchange Server and no IMAP. – Mayank Dec 10 '10 at 17:59
  • do you use an Archive? if so how large is the file? – Xantec Dec 10 '10 at 18:08
  • I store my old mails in a separate PST file which I don't load on outlook start up. It is pretty large in size (around 1 GB) but since it is not loaded when Outlook is started, I don't think that it can be reason for slowness, can it be? – Mayank Dec 10 '10 at 18:13
  • Microsoft Exchange is IMAP, sorry to tell you. – user3463 Dec 10 '10 at 18:41

I found that deleting the outlook connector addin for hotmail shortened my load time by 75%. It was taking over three minutes to load Outlook 2007. I have completely uninstalled Microsoft Live Essentials and my machine is running like it did prior to allowing the updates. Me thinks Live Essentials is a bad piece of work by Microsoft. But, what isn't.


Disable add-ins (especially the ones you never use), but start with all and then work backwards to see which slows down Outlook when enabled

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