Corona high quality denoising has no effect on IR, nor does Intel AI denoiser. Both of them are only compatible with regular rendering and also both are ignoring your RTX card, because they are running on CPU. Only Nvidia AI denoiser is compatible with Corona's interactive rendering, but it has to be enabled elswhere from main denoiser settings (look at previous message from TomG).
Regarding IR being faster than regular rendering, this is common misconception, but it's not true. IR is faster to start rendering and faster to show recognisable picture, but in the long run, it is actually slower than regular rendering. You can look at them, like at sprinter versus marathon runner - the former will be faster over 100 m distance, but it will run out of steam way before marathon finish line :]