P: Allow Selection of Fast (current) or Accurate Rendering in the Develop Module

Lightroom preferences should contain an option to enable the user to choose between "fast (but inaccurate)" and "accurate (but slower)" renderings in the Develop module. Currently, the setting is hardwired to "fast (but inaccurate)". The user should be given the choice of trading in speed for a better rendering (the latter is available in the Library module).

Some image operations (only noise reduction or more?) are not performed in the Develop module unless the magnification is 1:1. This means that at lower magnifications (such as "Fit"), one often sees grainy areas (such as grainy skies, when one has applied drastic HSL controls and/or the image has been pushed in exposure) which are shown to actually be smooth (e.g., due to activated chroma noise reduction) when one zooms in to 1:1. The graininess seems exaggerated in the sense that a normal downscaling of the noisy image to a "Fit" size should not show such course blotches of heavy grain, but something smoother. I find the resulting renderings very distracting and they make it hard to judge whether the overall colour of the blotchy area is as desired or not.

I agree that adjustments to sharpening levels, noise reduction, etc. should be made while looking at a 1:1 view. However, there should be a way to judge one's editing efforts on a downscaled image as well. Images are not always printed but sometimes just edited to be shown as downscaled versions, e.g., on the web.

I do not think that it is acceptable to be forced to go the the Library module to get a reasonable downscaled rendering of the current edits. It doesn't even make sense that the Library module shows a more accurate downscaled version of the 1:1 view than the Develop module. If anything, it should be the other way round as it would be excusable to lose accuracy in favour of speed while browsing (Library). However, the image editing activity (Develop) should always be supported with the best possible preview, no matter the magnification.

Ideally, this feature request would lead to the removal of any differences between renderings independently of the module in which they are displayed.

I do not only see differences regarding chroma noise reduction (resulting in Develop module views that are ugly in parts) but also in highlight rendering. There are quite non-subtle differences (regarding colour and extent) in how some highly saturated red/orange/yellow highlights are shown between the Library and the Develop module views.
Victoria Bampton has indicated that a bug is causing this behaviour.

The user should not wonder about which of several different renderings is the "correct" one, i.e., one that is closest to what an exported, downscaled image would look like. Will the latter look like in the Develop module, the Library module, or yet another way?

Summarizing, unless a user intentionally opts for faster, but inaccurate, renderings, they should be given the best possible rendering (which includes sharpening after downscaling) at any magnification. This should be true for all modules but in particular the Develop module should support this mode.

Ideally there would be a quick way (e.g., a keyboard shortcut, or a switch in the Develop module) to change the "fast" vs "accurate" rendering behaviour so that one may toggle between them, should the "fast" version be accurate enough for a particular set of images.

I had formulated this feature request as a bug report before, but is has been argued that the current behaviour ("fast but inaccurate") is "as designed" and hence, technically, there is no bug.