I'm pretty sure that's what everyone does after the first time they try a test encode and see the dismal speeds. It's a trick as old as time. The trick is to make that segment decision better than something like the YT algo that decides where to place an ad break.
Full disclosure I currently work for Bitmovin, but we work well on AWS, Google and Azure. We have some migration tools and are one of Microsoft's recommended alternatives since they are sunsetting Azure Media Services. Our Streams product is a simple, one API call solution that just works, similar to some of the things mentioned already, but we also have a pretty advanced API that can do whatever you need. We're also about to wrap up a beta for GPU acceleration with NVIDIA and make that publicly available.
