On 64 bit window 2003/2008 servers as soon as you give any .Net (.aspx) resource requests you would notice w3wp.exe taking large amount of memory in form of Virtual bytes.
Looking in task manager we would notice W3wp.exe Process/Commit size: 380 MB
Whereas looking into perfmon virtual bytes counter or in IIS 7 => Worker Processes.We would notice approx. 5.5 GB as virtual bytes occupied by w3wp.exe
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