Hi Rajesh,
Thanks for taking my advice.I got to know you have set a memory limit for this VM.To make you understand on the performance impact specially when we set a limit on memory/Cpu i'm providing you with a http://kb.vmware.com/kb/1033115. Good part is you know when exactly VM is experiancing performance issue(Every Monday) and that helps to you go ahead collect accurate snapshot logs Image may be NSFW.
Clik here to view.
.I'm also not sure whether you have tried migrating the VM to another host and monitored the same?If you are good at Esxtop you can also refer http://kb.vmware.com/kb/2001003
