Severe latency bottleneck detected on ISL / Trunk port

How to troubleshoot error "Severe latency bottleneck detected" on ISL/trunk port?
What can cause this problem and how a root cause can be found?


I faced this problem at one of my customers.
We received this alert on trunk created from two 8Gbit ISL ports between two 5100 switches.

Here is alert message:
Time    Level    Message    Service    Number    Count    Message ID    Switch 
Mon Aug 06 2012 20:32:05 CEST    Warning    Severe latency bottleneck detected at slot 0 port 35.    Switch    1241    1    AN-1010    XSAN01