Why is the receiving speed of outlook too slow?

Outlook has always been good, just like Word and Excel. If you don't think so, maybe you are not familiar with it. However, from Outlook Express to Office 2003 at the earliest to Office 2007 at present, the feeling of outlook is everything, and everything is improving. Only when receiving emails is too slow.
Now my network is 10 m optical fiber, and the download speed can reach more than 1 m. I think the speed should not be a problem, but how many emails are always B? After finding n methods, I was finally able to find a solution. It turned out that anti-virus software was a ghost, because I used Symantec's Enterprise Edition, this anti-virus software is actually very good. After it is installed, you will not feel that there is a anti-virus software running, but when there is a virus, you will find that it is actually working quietly, very good (of course, the enterprise version 10 and Vista versions are much better than 9, and the anti-virus capability of 9 is indeed not very strong ).
There are two main protections in it: file Real-time protection and mail protection. I removed the email protection function and re-opened outlook, it seems that Symantec Anti-Virus Software may slow down the interaction between the client and POP3 server during the download process.
What kind of emails do I have to identify with the naked eye? Besides, anti-virus software provides real-time file protection to disable this function! Of course, Symantec is expected to make improvements in the next version.