Best tile size on both cpu and gpu Recently did some testings with my pc setup (gtx 1660super, ryzen 2600 3.9ghz, 16gb 3200mhz). And was surprised by the fact that my gpu best performance was with 64x64 tile size. But not only that cpu alone was also showing best results with 64x64 tile size. The question is did the difference between tile sizes is gone with updates or something wrong with my pc or windows setup.

Blender 2.83; Windows 10 2004; very recent NVIDIA drivers
Starting from version 2.8

CUDA renders no longer need to use large tiles. In many cases rendering with a tile size of for example 32x32 will actually be faster now. When using denoising it may still be somewhat faster to user large tiles, but this comes with a high memory usage cost. (6da6f8d6da)

reference: https://wiki.blender.org/wiki/Reference/Release_Notes/2.80/Cycles
For 2.83 new changes:

For GPU rendering, adaptive sampling sometimes needs a bigger tile size for good performance. For combined CPU + GPU rendering, tiles rendered on the CPU and GPU may not match exactly. We will investigate automatic solutions to these problems for future releases.

reference https://wiki.blender.org/wiki/Reference/Release_Notes/2.83/Cycles