Technology in terms you understand. Sign up for the Confident Computing newsletter for weekly solutions to make your life easier. Click here and get The Ask Leo! Guide to Staying Safe on the Internet — FREE Edition as my thank you for subscribing!

Why Is Outlook so Slow to Receive Email?


When downloading email using Outlook, it seems to require all CPU power and
it takes forever. The same emails can be downloaded in seconds with my
smartphone or iPad using the same connection. Why does Outlook make such hard
work of it?

In this excerpt from
Answercast #71
, I look at an Outlook installation that seems to be having a
hard time writing information to disk.

Become a Patron of Ask Leo! and go ad-free!

Outlook is slow

My initial reaction is to immediately focus on Outlook’s need to store the
file on your hard disk.

My guess is (and this is just a guess, but it’s an educated one) that the
PST file itself is either full or fragmented or not compacted.

PST file is “slow”

In other words, Outlook is spending all of its time not in downloading your
mail (that part’s easy as you’ve seen with your other devices). Outlook is
spending all of its time (and all of its resources), trying to put that email
into its storage file, into the PST file.

So, I would do about two or three different things.

Check the disk

One, I would run ChkDsk /R
on that hard drive in case it’s a hard drive problem that’s causing Outlook to
have trouble.

A bad sector that happens to be in the middle of your PST could cause
exactly what you’re seeing.

Defragment the drive

I would defragment your hard disk, if you haven’t.

A fragmented PST file that is severely fragmented could easily cause the
kind of behavior that you’re seeing here as Outlook has to run around to all
different places in the PST file to update the location of your email, to add
it here, to update an index there, to update the list of your emails elsewhere…
So anyway, defrag the drive is what I’m saying.

Compact the PST file

And then finally, it’s worth considering compacting the PST file. If you’ve
done a lot of deleting of email and moving emails around and so forth, the PST
file itself can internally get kind-of sort-of “fragmented,” much like a hard
drive. If you defrag it, which in Outlook terms is “compacting it,” then you
can also improve its performance.

The way to do that is to right-click on the Personal
(or “Outlook PST,” or whatever it’s listed as in the left-hand
pane of your Outlook window); click on Properties and in (I
believe) Advanced (it may just be right there), there’s a
button that says “Compact Now.”

I’ll give you a warning: compacting can take some time. It can actually take
a fair amount of time if your PST is large. So this is the kind of a
thing that you might want to set up to run overnight. Set it up before you
leave work, set up before you go to bed… whatever, but let it chug on it

Final cleaning

Then to bring things slightly full circle… Because modifying the PST (compacting the PST) actually causes a lot of disk activity, it might also be
worthwhile to then (after the compaction is done) exit Outlook completely and
defrag your hard drive again.

It’s very possible that all of the manipulations that Outlook has to do to
compact a PST could result in a fragmented PST on the hard disk.

So those are the three things:

  1. ChkDsk /R;
  2. Defrag your hard disk;
  3. And compact your PST.

See if that doesn’t improve things quite dramatically.

End of Answercast #71 Back to –
Audio Segment

Do this

Subscribe to Confident Computing! Less frustration and more confidence, solutions, answers, and tips in your inbox every week.

I'll see you there!

1 thought on “Why Is Outlook so Slow to Receive Email?”

  1. Leo was correct when he stated “I’ll give you a warning: compacting can take some time. ” I had a pst file which was inflated to 20 GB. I let it compact, resulting in a file of 5.8 GB. This compacting took 25 hours and 40 minutes. The computer did not have to do other tasks during that period and was thus fully devoted to this task.


Leave a reply:

Before commenting please:

  • Read the article.
  • Comment on the article.
  • No personal information.
  • No spam.

Comments violating those rules will be removed. Comments that don't add value will be removed, including off-topic or content-free comments, or comments that look even a little bit like spam. All comments containing links and certain keywords will be moderated before publication.

I want comments to be valuable for everyone, including those who come later and take the time to read.