@WiteWulf this is very disheartening. Now I'm wondering if there is a widespread latency problem with the WRT3200ACM / WRT32X in OpenWrt 18.06 and Master. Your latency results much worse than even the R7800 used to have. Could you give us an overview of how you're running that test?
The R7800 was almost this bad for a while, but through patches and kernel 4.14 was mostly fixed: