September 1, 2016
Microsoft Outlook Running Slow?

One of the most common issues I run into is Outlook running slowly and becoming unresponsive.  If you use Outlook, you almost certainly have run into this once or twice- or hundreds- of times.  With a large chunk of our day spent writing and responding to emails, an uncooperative Outlook can become a frustrating delay to say the least.  In my experience, there are many reasons Outlook can become sluggish and there typically is no single cause, but rather a combination of settings and procedures that can help:

Keep your mailbox lean.
You’ve heard this one before from countless sources- and that’s because it’s good advice.  The less data Outlook has to manage, the faster it will run.  I personally keep emails no longer than one year.  If you need emails longer than that, you should be archiving them to get them out of your mailbox but still remain accessible.

Use folders to organize your email.
This makes it easier for both you and Outlook to find emails and also greatly speeds up searching.  You can use rules to automate this, which really makes it easy to stick with your organization setup.  Microsoft does recommend you have no more than 500 total folders; I would say half that is better.  Outlook 2016/2013/2010 has a 100,000 item per folder limit but I would recommend half of that again.  If you are keeping your email lean, you should not need to exceed that many emails in the first place!  Also for best performance, you should avoid keeping folders inside your inbox.  Instead, move them to the root of the account.

Clean out the deleted items folder.
This goes back to keeping your mailbox lean.  Deleting an email sends that email to the deleted items folder, which is still part of your mailbox.  It does not help much if you just delete and email without clearing it from the delete items folder; all you have done is moved it.  While a little too aggressive for me, Outlook does has an option to automatically delete items from the deleted items folder each time you close Outlook.  Instead, I apply the same rules to the deleted items as I do for the inbox as far as retention goes.  Also, I make judicious use of Shift-Delete on emails that I know I don’t need to keep (Shift-delete permanently deletes an email and does not send it to the deleted items folder).  Do be careful with shift-delete though- it is permanent.

Limit add-ons.  
One of the best things you can do- third party add-ons can slow Outlook down and cause lockups.  Only install add-ons that you absolutely must have.

Disable Antivirus integration.  
This advice seems to go against what you have always been told but can go a long way to keeping Outlook stable.  Your anti-virus is still protecting you; just not linked in with Outlook trying to scan every email as it comes in.    Microsoft also recommends setting your virus scanner to exclude outlook folders and files (oab,srs files in AppData\local\Microsoft\Outlook)

Set Outlook to save attachments for 999 days.
You won’t have to wait for Outlook to re-download attachments every time it access the email.

Setup Outlook to download the full email, not just headers. 
This at first sounds counterproductive.  If Outlook is set to only download headers, each time you access the email it has to connect to your server to retrieve the body of the email, which takes time.  Downloading the full email will keep it local so later access is much faster.  This will also speed up Outlook searches.

Disable hardware graphics acceleration. 
This one is not for everyone but is worth a try.  Outlook by default uses your computers video card directly to make display access faster.  Not all hardware drivers however work well with Outlook and this can cause Outlook to stall.   Turning this feature off can alleviate these types of issues.  You can find the setting in file/options/advanced under the Display heading.

Create a new profile. 
When all else has failed, try creating a new profile and let your mailbox rebuild.  Corrupt data in the profile can cause many Outlook issues, starting a new profile will re-create the databases and get you going again.