Reply to What dictates the output latency with a Native Instruments Z2?

I have a Native Instruments Z2. With the process buffer at 64 samples and the USB buffer at 1 ms, these are my latency settings: -

Processing = 1.3 ms
Output = 4.4 ms
Total = 5.7 ms

Someone else I know who is also using a Z2 has the process buffer at 128 samples, the USB buffer at 1ms, but gets better overall latency than me: -

Processing = 2.7 ms
Output = 2.0 ms
Overall = 4.7 ms

So what is it that dictates the output latency? Why is mine 4.4 and his 2.0?

Thanks.