Hi,
Maybe some other process is consuming CPU cycles, check with procmon or something similar.

>I have a major problem on one server. I have been trying to find out the reason in the last month by trying to collect more metrics on a very unique bizarre situation which happens only on occasional basis.
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>This has happened twice in mid October, once last night and once tonight.
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>I can see that the hit sent to IIS, from the browser, is being logged immediately in my Hit table. So, the time I sent the hit from the browser is properly represented in my Hit table. However, IIS does not want to respond to the hit right away. It will take about 5 minutes to process what seems to be an accumulation of hits in the queue. So, during that 5 minutes, no matter where we click on the Web site, IIS does not want to process them. Then, five minutes after, I can see all of them being processed at the same time in the same second.
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>Those are very small hits. We talk about 0.02 second here. Those are the hits I am testing when trying to simulate the issue. One thing that is difficult is that I haven't found the pattern to simulate the issue.
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>So, basically, ASP.NET allows the hit to be processed in our application. I get that in the Page_Init() event. However, the Page_Unload() event will not kick in because IIS or ASP.NET is blocking the execution for about five minutes. It is only when I started to analyze as well the IIS log that I was able to figure out more about what is going on. The IIS log will only log the hit when it is completed. But, my framework logs the beginning of the hit by created the record so I have the time stamp it was received. This is received as is. It works ok even if it takes five minutes for the hit to be processed. However, the completion of the hit in my framework will indicate numbers like 3 to 5 minutes for the entire duration it took to process the hit. Then, at the IIS log, as it logs only in one shot, it will log a time stamp at the time the hit was completed.
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>This is not database related. I have four SQL select in those hits. The total amount of time to process those 4 SQL select is 0.000 second.
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>But, there is something which causes a stop between the Page_Init() event and the Page_Unload() event.
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>I thought that this could be related to a new NAS we are using soon to be in production. That NAS is shared among other products that I have no idea about but I have been confirmed they should not be a factor. So, I thought that maybe if the NAS has not been used in a hit for a while that this would create some kind of pause until it restarts. So, I tried an IISRESET /RESTART. Then, I did the same hit that is subject to cause this situation. It worked ok. So, I restarted the server. I did the same test. It worked ok. I installed IIS over again and apply all the settings for the Web site. This did not change anything.
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>Those are Windows Server 2008 in a virtual environment with 2.8 Ghz CPU with 12 cores and 16 GB of RAM. Only one of them is having this behavior. We have it about one time out of 27 when I do the same hit. I tested that about 50 times on a UAT server. I never had a problem. This is also in production and we used that option about 12 times so far and never had a problem. We also have two other environments where I did that about 200 times and never had a problem. It is only occuring on one server and this is a real mystery.
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>That hit is the same I always used to start all my Windows Services. I have 26 Windows Services, known as robot applications, and when starting them, it will launch a request to several servers hosting those services where the path of the executable is from the NAS. We have each Windows Service probably defined for a domain account which has full rights on the NAS for what we need.
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>Anyone could have any idea on what else I could look at?