nView

nView is a Blender add-on for optimizing scenes based on what can be seen by the camera. It does this by detecting objects not seen by the camera, and either hiding them or masking their geometry to reduce the amount of visible geometry in your scene. This improves viewport speed and saves rendering time without compromising anything visually.

• Select only the visible objects!
• Automatically hide and disable collections or objects that reduce your performance, without affecting what's seen by the camera!

It supports all render engines, object types, and both perspective and orthographic cameras. It also supports detection of geometry within instanced collections and linked objects. My favorite features include:

• Bake object visibility to keyframes, accelerating viewport playback and render times!
• Mask out geometry outside of camera view!
• What about objects visible in reflections, or behind transparent objects? You can preserve those too!

Read the documentation for a deeper dive: https://blendermarket.com/products/nview-v3/docs