Memory speed under 4.4

What is the issue with the memory speed when using 4.4 kernel vs the newer kernels? More specifically - looking at this one - - I see the 4.8k memset number when using 4.4 kernel. Using 4.19 or 5.3 for example yields a much higher number - more like 8.2k. Is the problem that 4.4 doesn’t have good support for lpddr4? Or does that have anything to do with the numa support that got added after 4.4?