big .pst file and Outlook 2007 slowdown


I'm using Outlook 2007.
My .pst file has grown to 6 GB.
The performance of Outlook has decreased.
I have done .pst compaction (for the first time) but it didn't help.
In addition to that when I right click "Personal folders" and display folder size, the size shown is around 3 GB.

My questions are:
1) what is the reason for the gap between 6 GB (physical pst size) and 3 GB (personal folder size shown in Outlook)?
2) what shall I do to increase speed of outlook?
- use some external compression program to compress .pst? if so, then which one?
- increase number of .pst files?
- delete e-mails? :)
- change e-mail software and migrate my .pst file?
- any other ideas?
3) I found software called "SysInfoTools PST Compress And Compact".
It compresses all attachments to .zip files.
Are there any alternatives which perform compaction only - that is, they do what Outlook does but better? (as I said, Outlook compaction did not help me, maybe because I didn't run compaction on a regular basis and now the pst file is too big for Outlook to do the compaction right?)
I do not want all my attachments to be moved to zip archives.

thank you very much,
Who is Participating?
David LeeConnect With a Mentor Commented:
A smaller PST file is better, but, unlike previous versions, Outlook 2007 can easily handle PST file sizes up to 20GB without doing anything.  It can handle larger version through a registry setting.  While I'm not urging you to let your PST get out of control, unless you have evidence that the PST file is the problem, then shrinking it probably won't fix the problem.  

If you've compacted and the file did not shrink, then there are a couple of things you can try.

1.  Create a new PST file, export everything from the existing PST to the new file, compact the old file, re-import the data from the new file.
2.  Create a new PST file and make it the default.  Import data from the old PST file to the new PST file.
David LeeCommented:
Hi, Jarek.

What makes you think that the size of the PST file is related to the slowdown?
ja-rekAuthor Commented:
This is my guess. Nevertheless, I'd like to decrease the size of my .pst file since it may cause problems - at least that's what I read on the web.
ja-rekAuthor Commented:
Hi BlueDevilFan

thanks for feedback.
1. to what format shall I export from existing PST? I haven't done this before.
2. will I lose any data/settings like folder structure after this operation (export and import to new PST file)?

David LeeConnect With a Mentor Commented:
Hi, Jarek.

Export to another PST.  That way you don't lose anything.  You can also create a new PST and then use drag-n-drop to copy folders from the existing PST to the new PST.
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