VuGen gives the facility to use multithreading. This enables more Vusers to be run pergenerator. If the Vuser is run as a process, the similar driver program is loaded into memory for every Vuser, therefore taking up a large amount of memory. This limits the number of Vusers that can be run on a one generator. If the Vuser is run as a thread, only one example of the driver program is loaded into memory for the given number of Vusers (say 100). Every thread shares the memory of the parent driver program, thus enabling more Vusers to be run per generator.