"Play audio while scrubbing" causes major lag in Premiere

[Route Eleven]

After a couple hours of trying to isolate the problem, I discovered that my Premiere lagging woes were occurring only in timeline areas with audio. Video-only clips play back responsively and smoothly. But scrubbing over any audio was very choppy, and the audio would often cut out during playback.

After messing around in the preferences, I've found that "Play audio while scrubbing" was the cause of the problem. I've unchecked the box and now I'm back to work, but I wanted to ask if anyone out there knows why this is happening. Audio scrubbing is a useful tool and I don't want to leave this box unchecked forever.\

[excited_Genie16B8]

It's not commonly reported.  You're the first I can think of.  Unfortunately, I can't think of any explanations.  You might try the following, see if it helps narrow down the culprit.

Premiere Pro Troubleshooting Guide

[Warren Heaton]

Audio drop outs during playback are often a result of the sustained data transfer rate of the source footage being about the same as the maximum sustained data transfer rate of the storage media.

I'd take a look at what the MB/second required to play your source footage and compare that to what your storage media can sustain as a troubleshooting step.

-Warren

[excited_Genie16B8]

Audio drop outs during playback are often a result of the sustained data transfer rate of the source footage being about the same as the maximum sustained data transfer rate of the storage media.

That seems unlikely.  Audio is a very small fraction of the data rate.  If the issue were related to throughput, it's almost certain the video would be affected as well.