Performance and flexibility in image processing and rendering was always a strong focus of TYPO3. With constantly changing technology, we must keep up the pace and provide a few pieces.
First of all, as more and more people are using cloud storages in FAL (which are slower than local storage), image processing should not slow down page rendering. This is especially important as a ground step for further enhancements in TYPO3 Backend media management.
Secondly, as more and more different image sizes for one image is needed for a responsive webpage, image processing should not slow down page rendering. The aim for this initiative is to reduce the Time To First Byte (TTFB) for Backend and Frontend requests by asynchronous processing.