Lightroom: Render noise reduction and sharpening only at 100% and at export for faster slider response

It would be great if there were a performance option that turns off noise reduction and sharpening unless you are zoomed in to 100%. This would make the sliders more responsive. For every batch of images that i edit, i have to turn off noise reduction and sharpening, do the edit, and then turn them back on before i export. This is a pain and something that can be easily fixed. In summary, NR and sharpening would be turned off by default, but would automatically turn back on when viewed at 100% and would be turned on for the export.