How to: Specify 64-Bit Process Using Test Settings
By default, load tests are set to run as a 32-bit process. If you have a 64-bit machine, you can now run load tests as a 64-bit process by editing the test setting you plan to use with your load tests.
Visual Studio Ultimate
To run a load test as a 64-bit process
If your code or Web performance and unit tests were compiled as 32-bit/x86, but you now want to run them as a 64-bit process, recompile them. The options are Any CPU, or 64-bit.
For maximum flexibility, you should compile your Web performance and load test projects with the Any CPU configuration. Then you can run on both 32 and 64 bit agents. There is no advantage to compiling Web performance and load test projects with the 64-bit configuration.
Open the Test Settings file for your tests.
In the left pane, choose Hosts.
Select the Host Type that you want.
In the Run tests in 32 or 64 bit process drop-down list, select Run tests in 64 bit process on 64 bit machine.
Choose Apply and then choose Close.