Just an short update: I think my configuration is working fine. I figured out that the ping reply delay has more to do with the end device then with the switch configuration :) 
I am working with Differentiated Services to match traffic from a specific VLAN and assign a switch queue of 6 to give this traffic a higher priority than normal traffic. But I am not sure with this configuration. I've red much about switch traffic priority but I didn't understand it all i think.  Config: policy-map {policy name} in class {class name} assign-queue 6 exit interface port-channel 1 service-policy in {policy name} 
Network traffic priority best practices at switch level