If any one planing to buy and latitude E6540, would recommend you to stay away from it.
I have now owned this laptop from past 6 months and I could say this has the worst build quality.
Strangely two keyboard keys came off till now, and screen border area is such delicate that it might break anytime.
Product purchased before 6 months should look new but strangely the colour of the product is faded. P erformance is all about what kind of software you install but all I could say is this has one of the worst build quality among all Dell latitude products.