>I guess that's also because modern CPUs can easily handle very old systems, which were relatively slow, and hence software written for it had to be efficient.

>I guess that's also because modern CPUs can easily handle very old systems, which were relatively slow, and hence software written for it had to be efficient. It's that but it's actually worse than that: power aside, one hertz for one hertz, modern systems are generally much more recompiler-friendly than a GameBoy or Atari. The reason is that modern software is written using high level abstractions, you have well defined firmware interfaces, self-modifying code has become the exception instead of the rule etc... That lets you make simplifying assumptions that can speed things up greatly. For instance "I don't have to worry about self modifying code unless I encounter a call to the firmware's flush_cache method". That's better than "I need to be careful with every write to memory because it might potentially write to code instead of data or registers". Back in the days it wasn't rare to find timing loops that required cycle-accurate emulation, for instance because the drawing code expected that the delay between the interruption until a certain instruction was executed was precisely n cycles. I doubt many people do that on a PS4, actually I would be surprised if you could make something like that work between all the various hardware revisions and firmware updates. So older hardware generally requires the emulator to be a lot more strict which often means that you end up with a comparatively slow recompiler. Given the complexity of a recompiler compared to a simple interpreter it's simply not worth it anymore for these old systems.