Slow Attachment Downloads

[Sargow]

Good afternoon. I am a new to the BES environment and am having an issue with a new install of a BES. I have about 20 users and they are all working except attachments. If the attachment is under 1 meg it comes down with no issue, however if the attachment is over 1 meg it can take 30 minutes-1 hour to be downloaded. Does anyone have any ideas why this might happen?
Again Email and calender is not affected. I am running Bes 4.0.
Thanks

[GlenB]

You may want to monitor the CPU time and memory used by the Attachment service using windows perfmon. if it is heavily loaded you may want to plan to move the Attachment service to another server.