You need to consider the following when addressing latency:
- CPU speed of the computer
- The quality of the Audio interface
- Connection type - USB/FIREWIRE.
- The compatibility driver/operating system/ DAW.
- The amount of buffering selected on the DAW, measured in samples.
Latency can be proportional to:
- The number of audio channels used
- Number of Plugins used
- Sample Rate
- Bit Depth
- Amount of Memory
- Processing Power
Increasing the buffering size gives the computer more time to process plugins but also slows the response of the system.
On a Windows computer, the drivers transport the audio to and from the sound card to the CPU of the computer and from there to the speakers. It's different on a Mac as it uses core audio device.