Why is the memory manager in Windows version 1703 faster than the current Windows versions?

I tested the speed of programs in Windows version 1703 compared to the current versions, I made sure no anti virus or other background processes where interfering. Geekbench scores 13% higher in multi core tests compared to the latest Windows. When testing pure CPU performance there is no difference but memory intensive programs suffer about 10..15% in the latest Windows compared to 1703. Test were run on an 8th gen Intel i7 with spectre and meltdown mitigations disabled.
Does anyone know what changed in the Windows memory manager since version 1703 and is it possible to undo these changes?