The patch providing a speed boost for NVK is to enable loop unrolling for NAK, the Rust-written shader compiler that continues to be worked on for the Nouveau/NVK driver stack. Enabling loop unrolling up to a value of 32 iterations is enough to double the NVK performance in some instances.
M Henning who authored the change commented that the game The Talos Principle jumped from 9 to 18 FPS on his system.
Another user in the merge request commented that running Valheim on his GeForce RTX 4090M configuration was enough to boost the frame-rates from 45 to 70~80 FPS.
The improvement is a step in the right direction but due to ongoing work in both the Nouveau DRM kernel driver and NVK/NAK Mesa code it's likely to still be a ways before the performance is potentially semi-comparable to the proprietary NVIDIA Linux driver or competitive to the open-source AMD Radeon and Intel Arc Linux graphics drivers.