Most DAWs use buffers to help handle incoming and/or outgoing audio data. The size of those buffers can impact the amount of latency the system has. Lower buffer settings produce lower latency but will require more resources from the host computer. Note that the sample rate the system is running at will also affect the latency amount for a given buffer setting.

Here's an approximate ideo of how buffer settings affect the latency of a DAW system.

At 44.1kHz sample rate:

32 samples = 0.73ms delay

64 samples = 1.45ms delay

128 samples = 2.9ms delay

256 samples = 5.8ms delay

512 samples = 11.6ms delay

1,024 samples = 23.2ms delay

At 96kHz sample rate:

64 samples = 0.67ms delay

128 samples = 1.35ms delay

256 samples = 2.7ms delay

512 samples = 5.8ms delay

1,024 samples = 10.7ms delay

Note that many musicians and engineers feel that latencies below five or so milliseconds are unnoticeable.