DLC Slow over Ethernet versus Token Ring

We have multiple web servers running SNA using DLC over both Ethernet and Token Ring. Response times for the Ethernet servers are up to 10 times longer than response times for Token Ring servers ( 2-5 seconds for Token Ring versus 20-50 seconds for Ethernet ). Sniffers show no traffic congestion or bandwidth issues – the problem “appears” to be internal to the server: i.e., the communication between the NIC and the application. We can see data being returned to the server, but the application does not respond for up to 50 seconds.
Does anyone know of any specific issues related to SNA/DLC over Ethernet being slower than over Token Ring?