High latency for no reason?

[Nancy]

I think you'd better download a network analyzer ,which can determine what fraction of total transfer latency is due to server performance or network variation.
Also it can identify "Top Talkers" by monitoring network bandwidth and usage by capturing data packets transmitted over the network .
Just have a try.
1. Wireshark
http://www.wireshark.org/download.html

2.Capsa free
http://www.colasoft.com/capsa-free/

3.Angry IP Scanner
http://www.angryip.org/w/Download

4.PRTG Network Monitor Freeware
http://www.paessler.com/prtg

5.Microsoft Network Monitor
http://www.microsoft.com/en-us/download/...

Hope it helps.