If your talking about a radiator, I've heard that moving the coolant too fast being bad is a myth. I've always thought it was a myth. The explanation I always hear is "it goes through too fast to lose any heat". There may be another reason, but I don't believe that one. If it was going so fast that it was making more pressure, I could see more heat being created just through pumping. But I think a heat exchanger cools a certain amount of BTUs for a given temp and flow of coolant.No kidding. It's also a well known fact that pushing the coolant too fast will also cause issues.
Of course, in this instant, everything is backwards. (The liquid is cooling the air) But I still think it applies the same.
Do you have a tech site or source that explains your statement?