Troubleshooting the number of deployment threads
You can configure the number of threads that actually deploy content, as expressed by the Workers property of a Queue in the Content Deployer configuration file, deployer-conf.xml.
The sum total of the values of the Workers properties of the various Queue elements in your Content Deployer configuration file represents the total number of deployment threads that can be active at any one time. This number should be somewhat higher than the number of CPU cores on your server. You can check the CPU load to tweak the ideal number of workers.
By default, the number of workers in each queue resolves to 10, and the total number of workers is 30. By setting an environment variable queueWorkerCount, you can change the number of workers per queue to a higher number, and the total number to three times that amount. To configure different numbers of workers for each queue, edit the Workers property for each Queue directly in deployer-conf.xml.