Setting up Aether SX2

 There are steps you can take to improve AetherSX2's performance, and in fact, the developer has been testing it a lot on their POCO F3 with the Snapdragon 870. There are a ton of settings you can tweak and play with, but there are only three that I've actually modified.

The first setting you can tweak that arguably matters most is the GPU renderer. You can choose between Vulkan or OpenGL, and the performance you get will depend on the device you're using and the game you're playing. For example, you may have better luck using Vulkan on the MediaTek Dimensity 9000 instead of OpenGL.

If you haven’t heard of the Khronos Group’s Vulkan Graphics API, think of it as an alternative to graphics APIs like OpenGL or OpenGL ES. It’s backed by companies like NVIDIA and Intel, and it’s intended to give developers more options when they’re programming cross-platform games. It also has a lower CPU overhead, which in turn can lead to better performance. As Tahlreth says, OpenGL is only faster in some games because it has framebuffer fetch. Your mileage will vary as a result.

The next option is underclocking, which I've found has great results when underclocking to 75%. The third and final one is a new option added in the most recent AetherSX2 update at the time of writing, and that is "skip presenting duplicate frames." It attempts to detect the game's internal framerate and prevents it from presenting duplicate frames. Combining this and underclocking turned games like Need for Speed: Underground 2 from borderline unplayable to running at a consistent 100% speed.