When increasing the maximum number of threads for a MID Server in ServiceNow Discovery, it's often necessary to also increase the memory allocated to the MID Server application. This is because more threads can result in higher memory usage as each thread may consume resources while performing discovery tasks.
Increasing disk space, updating ACL rules for CMDB tables, or increasing the MID Server max payload size are not directly related to the number of threads used by a MID Server. References = ServiceNow Discovery documentation, especially sections discussing MID Server configuration and performance tuning.