Charging Question

Alright team, i have a question; Currently i am using the Hyperion EOS0606i charger. When i am charging high mah batteries like my Turnigy 5s 5000mah batteries it only charges them at around 2.5amps, am i wrong to assume that they should charge at 5amps, i mean right now it takes over an hour to charge one @2.5amps. It might be time to upgrade chargers now especially with 5th scale brushless cars in my arsenal. Does anyone have suggestions as to which charger as should buy next if my current one isn't up to the task? I prefer the Hyperions because they are simple and have lasted me much longer than any other charger i have owned, but i am willing to look elsewhere. Also if i get one that requires a power supply, which one should i get?