High Memory Usage

[Scyberian]

I must first admit that I am Sprint Indirect dealer, because I had a customer come in to my store with a Mogul running stock config, that was using approx 85%-90% memory used. There were no unusual programs or other "typical" reasons for the high usage. The only thing different from mine was the fact that I have the 6.1 beta still (as opposed to his 6.0) and the fact that he was on his company's Exchange Server. Any advice as to how to reduce his memory consumption?