If you see a spike of latency, you should do a call path mapping from the PathSolutions server IP address to the IP address of the device with the spike of latency & jitter. You should look for high utilization on any links between the two, as the high utilization would lead to increased latency and jitter along the way.
You should also look at the router and switch CPU utilization for devices along the way to see if a router is CPU starved at the time the latency and jitter occurred.