A method for measuring performance of virtual desktop services offered by a server including a processor is described. A first encoded watermark is embedded into user interface display generated by a virtual desktop when initiating an operation. The first encoded watermark includes pixels identifying the operation and indicating its initiation. A second encoded watermark is embedded into the user interface upon completion of the operation indicating completion of the operation. An action performance time is then computed and stored in a memory. Multiple performance times may be compiled from multiple operations of multiple virtual desktops to assess the performance of the system as a whole.