We’re currently working on a project in which numerous cameras are set up, feeding streams to planes in game like CCTV screens. There are currently 12 cameras set up in various places that all render to the panels that act as CCTV screens.
The method we are currently using is really heavy on performance and drops FPS into the single digits. The current workaround we are using is that the CCTV screens render a flat texture render of the scene it is looking at until something comes into view, at which point the actual camera feed becomes active.
The problem is, we want cameras to be panning and we want moving things in the environment, which obviously doesn’t work with static renders.
Try changing the resolution of the texture you capture too.
You could also try limiting the update rate and/or manually update it at a set rate by ever so slightly adjust its position (rotation?) as required.
If and when the player gets close/focuses on a particular screen, speed it back up and increase the resolution.