I have a 10GbE network at the house and often transfer large files between servers/computers/etc. The only way I see the full transfer speed on my network is if I transfer from SSD to SSD. If either ends have a spinning hard drive, the transfer times are doubled.
Using that same logic (flawed logic), I figured that recording straight to the M.2 drive might clear up a bottle neck when infact it only complicated the system. After ditching the M.2 drive and recording direct to the WD purples, it's been smooth sailing. Another thing I did in "Clips and Archiving" is to click "Do NOT monitor free space" I just set up the limit size lower than the size of my drive. Right now, I'm only recording alerts. All my clips are going to the "Stored" file. I'm not using "New" or "Alerts". It seems to be working fine this way. I've been reading that the general consensus is to record full time just incase something is missed. I will probably do that in the future. But, it's been working great the way it is now.