The default API (application programming interface) used by E-Prime 1.0, E-Prime 1.1, E-Prime 1.2, and E-Prime 2.0 is DirectSound capabilities offered by DirectX.
Under Windows XP, the DirectSound API provides a thin layer between E-Prime and the hardware components/drivers of the sound playback devices.
This provides a low latency sound playback in E-Prime where the latency result is correlated by the hardware implementation.
In Windows Vista and Windows 7 (and beyond), the DirectSound API no longer is a thin layer between E-Prime (or any application) and the sound hardware, but instead sits on another management layer.
This results in poor performance on the same hardware where lower latency was achieved on the same hardware using Windows XP. Typically these results average in the 30ms range for startup.
Therefore, PST does not recommend paradigms requring startup latency values of less than 30ms under Windows Vista or Windows 7 for E-Prime 1.0, E-Prime 1.1, or E-Prime 1.2.
For Windows Vista and Windows 7 usage under E-Prime 2.0 for low sound startup latency, PST recommends using E-Prime 220.127.116.11 or later and using either the ASIO or Core Audio/WASAPI API options available under SoundDevice properties in Experiment Object.
For more information on how to determine if ASIO or Core Audio/WASPI is compatible with your system, please see INFO: Use of SoundTester to determine machine compatibility with ASIO or Core Audio/WASAPI  for more information.
Please see INFO: Sound Latency - Not all sound cards provide optimal millisecond timing  and INFO: Operating system (Windows 10, Windows 8.1, Windows 8, Windows 7, Vista, and XP) support in E-Prime  for additional information.