If you are like me and have used Outlook 2010 with IMAP for your e-mail service with Gmail, you likely noticed how slow, and sometimes unresponsive Outlook 2010 will become for a period. The freezes became so bad that I really wanted to switch to another e-mail service to stop the freezing and slow Google e-mail. Luckily, there are a few steps you can take to ensure a better quality of service when using Gmail or Google Apps via Outlook 2010 with IMAP. I assume this would work for other versions of Outlook like 2003 and 2007 as I would think they have the same problem however the exact steps outlines below are for Outlook 2010.
1. Unsubscribe The Gmail ‘All Mail’ folder
Step 1
Remove the subscription to the Google ‘All Mail’ folder.
This provided the biggest relief for me because with this enabled, everything was being synced two times. Click on the inbox folder of the account you want to unsubscribe “All Mail” for
Step 2
Click the Folder tab at the top of the Microsoft ribbon in Outlook 2010.

Step 3
Click the IMAP Folders button in the middle of the ribbon.

Step 4
Change the middle box from All -> Subscribed and click query

Step 5
Highlight at least the the “All Mail” folder and click unsubscribe. You could do this to as many folders as you want to unsubscribe. I imagine having only a few subscribed would yield the best results but only disabling all mail made a huge difference for me.
2. Two copies of all sent mail?
Make sure you disable Outlook’s feature that saves mail in the sent folder. Gmail already does this so having both enabled yields to duplicate sent messages.
Step 1
Click the file menu in Outlook 2010
Step 2
Click Account Settings > Account Settings.

Step 3
Highlight the account you want to change, and select Change. Then click More Settings in the box that appears.

Step 4
Under the Sent Items tab, select Do not save copies of sent items.

I hope this helps some of you out who many hate how slow Outlook 2010 is with Google’s IMAP. For those of you who may even have two gmail accounts, one for Google Apps and one Gmail account like me may notice an even bigger difference.

Thanks a lot – great help. Tried for hours to figure out how to do this.
No problem. It took me hours to figure the above out so I’m glad I could help.