You need to analyze the load on your server along with the server's capabilities and configuration.
How many mailboxes do you have? What is the speed of your network, and how is your NIC configured? If you have a 100Mbps network but your NIC and/or switch are configured incorrectly, your users will suffer. Your NIC and switch ports should be manually configured for 100Mbps/full duplex, and your client workstations should be as well. A mismatch will have a serious effect on overall performance.
If your server has insufficient RAM, performance will suffer as the IS grows. One of the least expensive performance enhancements you can make is to put as much RAM in your Exchange server as it can handle. If you simply have too many mailboxes for the hardware you are using to handle efficiently, consider adding a server to your Exchange site and moving some of the mailboxes to it. This would be more effective than adapter teaming (more accurate term than load balancing in this instance) if the processor simply can't handle the load. If your system is simply too slow, improving network throughput will not result in any improvement in performance.
More simply put, you need to do a little analysis to determine where your bottleneck is - the server itself, the network, or just a configuration issue.
In your latest posting, you say that the store.exe is running high. Do you mean that it is using a lot of processor time, or that it is using a lot of memory. It is normal for store.exe to consume a great deal of memory, but it should not consume a great deal of processor time.
As for the maintenance issue, if you have only one single blue square, that would indicate that there is only one hour (or 15 minutes, depending on the selection on the right-hand side of the tab) scheduled for IS defragmentation each week. Make the change I suggested in my first post (making sure the window is set to display the time in one-hour increments). Since it has been a long time since the IS has been properly defragmented, I would increase the amount of time to at least 4 hours per day. After a week, or so, check the event log to see how much fragementation is being reported. I can't remember the event ID you need to look for, but you shouldn't have any trouble finding it.
If you want to perform a manual defrag, schedule it for after-hours. Make sure you have free space on the partition containing the IS that is equal to 1.1 time the size of the priv.edb (if the priv.edb is 4GB, you will need 4.4GB of free space). Perform a tape backup before proceeding. Stop the Directory Service (this will cause the IS and MTA to stop). Open a command (DOS) window, and enter: eseutil /d /ispriv.
I recommend you let the online process run for a few days before deciding if a manual defrag is necessary. You won't see a decrease in the size of the database files, as the online process does not recover free space. You should start to see an improvement in performance after a few days, though. How long it takes to see improvement will depend on how large the database is, and how much fragmentation there is. Be patient. Letting the automatic processes work is always preferred to manual intervention.
