i normally get both the long hourglass stutter, and the micro stutter.
using a rift s on a plenty powerful system.
does not seem to matter what quality settings in game i choose.
however using the occulus rift debug tool, and setting adaptive gpu performance scale to OFF and asynchronous spacewarp to disabled fixes it. and i can run hi settings without freezes.
bonus points, use pixels per display and set it 1.2-2.0 or so to increase the resolution of the displays. (warning with this, it may impact fps if set too high, and because you are in effect showing a higher resolution image it may change the point of aim just a bit between settings. but it really makes things much clearer if your computer can handle it. i find even 1.2 is a noticeable improvement)