Application slowness over MPLS. Latency and bandwidth appear to be fine.

Hi, I've got a strange issue I was hoping someone could help me with because I cannot for the life of me figure it out. We have a new site with a 100Mbps MPLS circuit. This circuit is from Zayo Communications but the last mile carrier is CenturyLink. We're seeing application slowness with a few of our applications (GE CPS EHR, Biscom Faxing, others). Internet traffic, speed tests all seem just fine. These applications use a combination of HTTP, SMB, LDAP protocols. The slowness is anywhere from 5-10 seconds slower than all of our other sites and is consistent. This is the only circuit we have that routes through CenturyLink as the last mile. Consistent ping times range from 10-12 ms while our other circuits are closer to 2-5 ms back to our primary data center.

I have tested bandwidth and we are receiving close to the 100Mbps. The slowness still occurs after hours with little traffic. I've verified our MTU settings, no errors (All Dell routers/switches), no fragmentation that I can see or test for.

Any clues on what I should look for? I have a ticket open with Zayo and so far intrusive testing has not shown any issues with the circuit.

Thanks for any insight!