Asynchronous Thread Queue (ATQ) Average Threads Monitor. The number of ATQ threads in usage is high which could impact throughput of client requests.
There is a fixed number of available threads for servicing requests. The default and recommended configuration is 4 per processor core. If all threads are in use, additional requests will sit in the queue until a thread is available.
Possible causes include the following:
The domain controller needs resizing.
One or more other domain controllers failed, and their load transferred to this domain controller because it is now the closest available domain controller.
An application is placing a heavy load on the domain controller. This is usually caused by inefficient, CPU-intensive operations such as non-indexed queries.
The domain controller is critically low on memory.
The domain controller is under a denial-of-service attack.
View the overall system performance of the machine to determine if it needs additional resources.
Add additional domain controllers to help load-balance the load.
Ensure that there are a sufficient number of DCs hosting DNS.
Capacity Planning for Active Directory Domain Services