IIS Number of threads worker process for ASP.NET application
Solution 1:
We were facing similar issues and we resolved the same by increasing the number of worker processes instead of threads. We had 5 web applications, all hosting ASP.NET REST APIs and each of them were assigned individual AppPool. However, still we were facing spikes which were generated from the slow database/IO calls running on a single AppPool.
We then started searching around how to increase worker processes and if that would help relieve the request choking. We found this article helpful. https://medium.com/@sanjay.rajak/does-api-response-fast-if-maximum-worker-processes-is-more-than-1-4b877af6b951
We did not change anything else, no change in CPU or memory setting for the AppPools, but still the application performance was much better with very low queueing.
Virtual core count in VM = 6 Maximum Worker Processes = 3
Check if this works.