Not sure about all DAWs...but some have the ability to show you the CPU/HD/RAM usage during mix playback, that way you have a real-time view of what's going on as the playback hits various tracks/plugs, etc.
I have it on my DAW, Samplitude ProX...it comes up as an info bar at the bottom of the project window if I turn it on. I"ve used it occasionally to check when setting up the DAW, to see what kind of limits I was faced with...and there are only a few cases where any of those three things are pushed harder...otherwise, my system has enough spare power/speed to cover most of my needs.
Buffers have an effect on the playback and the crackles...though your monitoring settings also can come into play, if you have more than one option for monitor settings. Like with my DAW, there are different "engine" choices and what I want to monitor...so those two things go hand in hand.
AND! If your DAW does not have that facility you can download a 30day demo of ProX .
I love it but cannot justify the cost. Wish they would do a "lite" version at 50-80 quid as Steinberg and others do.
MAGIX "Home Studio" software just ain't the same.
Dave.