There is also Qualcomm Fast Path: Qualcomm Fast Path For LEDE
There is a github repo for the Deco P9 (That's an M4R with additional Powerline board) that has Qualcomm Fast Path patched into it: Deco P9 switch config - #17 by dietcoke73
I haven't looked into this myself but maybe it's worth checking out for you to get more speed out of your deco.