I reinstalled Gargoyle 1.11.x from here:
http://lantisproject.com/gargoyle_custom/mvebu-1.11.x/
I was able to go from openwrt 18.06.1 directly to Gargoyle using the system upgrade file there. I didn't try to save any settings.
I don't think that's the latest build but it's what I used for the testing purposes. I didn't have a link and it's not that easy finding these beta files from google.
I immediately got full speed on my WRTacs v.1. I tested three times on dslreports speed tests. Download ranged from 462 to 482 down and a high of 21.94 up. The results didn't vary much in three tests. Bufferbloat was D
With QoS turned on and using the defaults. I set download bandwidth to 400000 and upload to 20000. I rebooted the router.
I ran DSLspeed tests another 3 times and got between 188-198 down and a high of 19.27 up. Bufferbloat improves to A or A+
I then turned off bandwidth monitors using putty and the stop/disable commands:
/etc/init.d/bwmon_gargoyle stop
/etc/init.d/bwmon_gargoyle disable
Again rebooted the router.
DSL speed tests showed little gain from turning off BW monitors.
I ran another three tests and the results were
198-204 down and a high of 19.x up
A last test was with BW monitor still off but ACC checked in the QoS settings.
Speed dropped another 10mbps or more with 3 tests between 181-190 down. Upload still around 19.
I much prefer Gargoyle's interface and ease of use but will probably put Openwrt back if I'm concerned enough with bufferbloat that I want to run QoS. There is just too much of a difference in QoS performance between Openwrt and Gargoyle.