The first beta of Krita 5.0 came back in August with UI improvements and better performance along with supporting newer image formats, an all-new MyPaint brush engine, and a variety of other features.
With Krita 5.0 Beta 2 there are more than 700 fixes plus many other changes. Krita 5.0 Beta 2 has a rework to its GPU-accelerated canvas that should lead to better performance particularly for HiDPI setups. This rework has a new means of uploading image textures to the GPU for delivering better performance.
Krita 5.0 Beta 2 also has translation updates and a wide variety of fixes throughout the massive codebase.
More details on Krita 5.0 Beta 2 along with downloads for this new test release can be found via Krita.org .