You can enhancing the number of TruClient Vusers using Terminal Services.

Each session has its own GDI object limitation thus, one can multiply the available GDI resources by the number of opened sessions.
In general, enhancing the number of Virtual Users in a load test with terminal services, depends on the machine being used and the AUT resources utilization.
As a specific example: running a test on a machine with 64GB RAM and 32 logical processors where 110 Virtual Users consumed ~57600 GDI objects, can be enhanced to 330-340 Virtual Users with terminal sessions.
In addition, the GDI Object handle per process limit is specified in the registry value:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWindowsGDIProcessHandleQuota

This value can be modified on a load generator using ''regedit''. While this value can be increased and may allow additional TruClient Vusers to be supported, it is recommended that adequate testing is performed to confirm how many TruClient Vusers can be supported (per process) without any increase in response times. When increasing TruClient Vuser response times are observed then the appropriate action to take is to add additional Terminal Services sessions. Each such session will use a new process and will allow additional TruClient Vusers to be supported on a load generator. For more information on GDI Object handles see:
http://msdn.microsoft.com/en-us/library/ms724291(VS.85).aspx

I hope this helps