Link: https://github.com/allkern/iris/releases/tag/0.20-alpha

Github dev comment: Wow, it's been so long since the last release I can't even remember what I've been working on! Just kidding, I've been working very hard on integrating a hardware renderer and molding Iris into a usable, user-friendly emulator, so many things have changed since the last release I can't even recall all of them, here's a non-exhaustive list of important changes:

Implemented Parallel-GS, a high-performance, Vulkan-based compute GS renderer by Hans-Kristian Arntzen  
Features:  
    High accuracy  
    up to 16x SSAA  
    Overscan, etc.  
Added game controller support  
Added input remapping  
Added support for SDL game controller DBs  
Added support for several disc image formats (CHD, CSO/ZSO, CUE)  
Added support for shaders  
Added a CE-like memory search tool  
Merged preliminary PSX DESR support  
Added automatic system detection based on the loaded BIOS  
Added support for screenshots  
Added experimental support for ImGui viewports (native windows for ImGui windows)  
Added a number of theming features: App theme and codeview theming  
Improved first-time-use experience  
Added support for loading NVRAM and flash dumps  
Added memory card creation tool  
Added preliminary support for audio CD loading  
... and an insane number of minor fixes and stability improvements.  

Games like Capcom Fighting Jam/Evolution and the Guilty Gear series (X, XX, Isuka, etc.) are now playable at decent speeds or even full speed, provided you have a decent GPU.