Siavash Tehrani

One thing that can be handy is the "follow current node" toggle in the Scene Graph Tree pane. When it is disabled your SGT will only show the scene graph of your currently displayed LOP. When it is enabled, it will show the scene graph of whatever LOP you have currently selected, causing it to re-evaluate the stage every time you select a different LOP.

AlekseiM
as I wrote in the first message, I have already tried to make a proxy in the form of a simple cube and even in the form of a single point, it is quite funny when simply imported points work perfectly 120+ fps, and assigning one point to these points as an instance completely breaks the display and drops performance by 1 fps, while visually they are identical

You are right Aleksei, once the point count goes into the tens of millions, the instanced points display slower vs loading the raw points. I wonder if that's expected behavior due to some kind of overhead? Maybe SideFX can chime in.

Sounds like a viewport performance issue. The Instancer LOP is displaying your prototype geometry as-is and doing distance based culling when the Scene Polygon Limit is exceeded.

A few things you could try:
1) Have a proxy purpose on your prototype assets, preferably one that's less than 10% of the render purpose poly count.
2) Set the draw mode on your prototype to Box or Axis with a Configure Primitive LOP before plugging it into the instancer.
3) Create a point in a SOP Create, configure its purpose to proxy, and define that as your asset's proxy geo before plugging it into the instancer. This can also be done as an override on assets that already have a proxy purpose. That should give you the same viewport performance as displaying the instancer points.
4) Configure the draw mode on your entire instancer to a single bounding box if you don't particularly need to see it outside of rendering.