Several things can cause Outlook to start slowly:

  1.  Outlook in Safe mode. Go to Start, Run, then type
  2. outlook /safe

If Outlook starts normal in Safe mode, Check one of the following:

The outcmd.dat file in the application data\microsoft\outlook folder might be corrupt.

  1.         Rename or delete this file while Outlook is closed.
  2.  When you restart Outlook, the folder will be recreated.

The view is corrupt.

  1. Start Outlook from the command prompt by typing
  2. " outlook /cleanview " to fix this problem.

 

A message in the Inbox is corrupt.

  1. Start Outlook in Safe mode, then move the Inbox messages to another folder.
  2. You will lose your mailbox contents.

An Outlook add-in is causing a problem.

  1. Click Tools> Options>Other> Advanced Options
  2. Click COM Add-Ins;
  3. Click Add-In Manager; then clear all add-in check boxes.

 

If Outlook doesn't start normally in Safe mode:

  1. You can also try to disable Windows Messenger integration.
  2. To do so, Click>Tools>Options>Other
  3.  Then clear the "Enable Instant Messaging in Microsoft Outlook" check box.