[ralphael]

I agree, by using var you need to name your variable better therefore making your code more readable. Rather than relying on the interface/class definition to explain to someone why you used "obj".

[quickthrower2]

To var or not to var is purely a "tabs 'n' spaces" debate, but doesn't affect performance.

[jenscow]

It will affect the performance of someone trying to read your code.