It may help to decrease the Thread Pool size if:
- Your server has limited memory (i.e. RAM). Regardless of CPU speed, a server with limited RAM should limit the amount of concurrent processing performed (i.e. threads used) in order to limit memory usage.
- All (or almost all) of your processes use only short-duration activities. In such a scenario, it may be faster for the server to process all activities sequentially (more or less) using a small number of threads, than to concurrently process the same activities. In such a scenario, the server resources required in order to split the server's CPU cycles between multiple threads may actually be (slightly) slower than simply waiting for any activities currently being processed to be completed.
- The opposite of any of the items in the previous list is true. However, note that decreasing the Thread Pool size will rarely result in dramatic performance improvements, so you typically don't need to fine-tune the Thread Pool size below 50.