I observe a significant slowdown at two gigabit locations.
A few month ago I mesured a download speed of around 900 Mbit/s
With latest builds the max speed I measure using speedtest cli on the router is ~580 Mbit/s
Hardware and settings are unchanged and IPS is turned off
Try to boot OpenWRT from a USB-Stick (so your current setup is not beeing affected by this) and check if your performance increases as significant as in my setup mentioned in my thread so we can confirm our problems are linked. Alternatively you could boot another distri like arch but you have to set serial as a kernel parameter.