Let us gather some essential information. Since now all essential driver systems are supported for the most common operation systems on a PC, we shall collect the amount of CPU usage.
On a Windows 10 PC with 48 Mo on an I7 3,6 gHz and a 10 track mod (1 is a send) at 48 kHz you got:
An average CPU load about 34 % using ASIO on an external device (native). Buffer: 128 samples.
An average CPU load about 26 % using WASAPI on an external device.
An average CPU load about 24 % using direct sound on an external device.
An average CPU load about 31 % using ASIO on an internal device (realtek & ASIO4all).
An average CPU load about 26 % using WASAPI on an internal device.
An average CPU load about 25 % using direct sound on an internal device.
I could imagine, I created 36 tracks with an amount of 25 % at 44.1 kHz using AFA and a crappy Lenovo Ideapad (Realtek) 12 years ago.
I couldn`t test it using port audio.