Hi Muhammad,
One thing to understand here is how ping works on cisco boxes, when pinging own interface IP address.
On Cisco Boxes, when you ping own interface IP address, it actually throws the packet out on that interface and then takes it back. So if you are getting more latency, it can be due to various other factors, which can be natting, link over-utilization, etc.
However, I'm here just point how ping to own interface works.
HTH,
Smitesh
