I am cutting on a Macbook Pro Avid Media Composer system, and find that when I have the timeline set to show waveforms, the system delays for at least five seconds every time I make a change, zoom in or out, or display a different part of the timeline. It didn't used to do this, but the problem seems to be getting worse. When I turn off waveform display, the problem goes away.
I'm cutting with DNX 36 footage, and the problem persists even with just one audio track. Even after the waveform is drawn, there is a long delay.