Many of us have encountered "pauses" in playback, since at least PrPro 2.0. For most, there seems to be no rhyme, or reason that has been found - no commonality.
That said, these pauses can be very specific to one's Assets. If this is the case for you, please let us know about your source footage, and also your Project/Sequence Preset. There might be an issue there. Also, does you playback stop at the same point, or is it totally random?
In the situations I mentioned above, the total randomness negated all efforts to pin-point the why. Sometimes it would be at a Transition, and the next time in the middle of a Clip. Sometimes it would be on a tiny Timeline with only one Clip and others would get it with long Timelines and many Clips. In these cases, the source footage would be DV-AVI Type II's and it didn't seem to matter if any Effects were added, and Rendering (when necessary) had no common result. In my cases, a Timeline would sometimes play perfectly a half-dozen times, only to halt at random points the next.
Good luck, and please let us know more about your Assets and your Project/Sequence. Also, a bit about your system will possibly help, especially the I/O sub-system, i.e. your HDD's, their size, speed, free space, controller type(s) and how they are allocated.