Probably it is iphlpsvc causing the problem. This is the service description:
"Provides tunnel connectivity using IPv6 transition technologies
(6to4, ISATAP, Port Proxy, and Teredo), and IP-HTTPS. If this service
is stopped, the computer will not have the enhanced connectivity
benefits that these technologies offer."
If this service is the problem, it would probably be because your machine is a part of some funky network configuration that iphlpsvc can't easily handle, thus causing the CPU spike. The reason why I think it is iphlpsvc is because that service is known to cause system issues when it's in situations it can't handle very well. See this thread for various issues (along with various solutions) to problems with iphlpsvc: http://social.technet.microsoft.com/Forums/en/windowsserver2008r2general/thread/ba9f0968-9275-434f-9e40-ec0621c3a35a
If my guess is wrong:
In the event iphlpsvc really isn't the problem, the good news is you've already done the non-obvious troubleshooting part, which is to find out the services hosted by your offending process (netsvcs winsvc.exe).
From there, it's going to be a process of elimination. Disable each service one-by-one and check the cpu usage afterwards to find the one that is causing the offense, and you will have root cause.
You have 12 hosted services. On my particular, superbly-running machine, I have 15:
Looking at the common ones and finding the ones unique to each system, we can observe that you have the five following hosted services running in your netsvcs image that I do not:
So those might be the first suspects to try disabling first. Either way, it will be a process of elimination. One of these services is causing the netsvcs CPU spike!
Now, whether that is ultimately causing your webapp to run slowly is a whole nother story, but, your hypothesis that it is netsvcs sounds reasonable for now.