Most of the updates are about long term support the performance gains are a side product.

This driver was one of the earliest open source drivers developed by AMD. The point of the driver is to convert OpenGL (instructions games give to draw 3D shapes) into the low level commands a graphics card uses.

A library (TMSC I think) was written to do this, however they found OpenGL commands often relied on the results of others and converting back to OpenGL was really CPU expensive.

So someone invented NIR, its an intermediate layer. You convert all OpenGL commands to NIR and it uses way less CPU to convert from NIR to GPU commands and back.

People in their spare time have been updating the old AMD drivers so they use the same libraries, interfaces, etc.. as the modern AMD drivers.

This update removes the last of the TMSC? usage so now the driver uses only NIR.

From a dev perspective everything now works the same way (less effort) from a user perspective those old cards get the performance bump NIR brought.