Hi Andrew,
This is not entirely true. Unity can use both Forward and Deferred. And with Unity5 they have created an even newer Deferred method that has built in capabilities of doing physically based rendering. Instead of many small shaders to cope the permutation shader problem, they generate the phyiscally based shader based on the input textures/values.
Going from HDR to LDR is not the problem.
I think it has very much to do with all the ‘additional render targets’ that are created in the background to do the post processing (much as you said). However, I put post process blend weight to 0 and turned all of the post processes off as far as i am capable of doing so from the editor.
Yet the performance of the 2DSceneCapturers is not increasing, this is very strange.
In Unity you have to Add all the post processes yourself or it will not be available, this works better because you cannot accidentally render in a slower way then necessary due to effects that are ‘not’ needed.
Perhaps I am missing something but i cannot find how i can get more control of what post processes are applied when doing a render other than just setting intensity values to (0 = off according to docs) and set blend weight to (0 = off).
Furthermore, it has come to my attention that when moving a 2DSceneCapturer around (with some large render texture eg 2048x2048) the FPS is incredibly spike due to allocations and releases of memory of more than 1 GB (when checking task manager). The resolution is not changed when moving the object. It very much feels as something is wrong.