Well, there is this thread that might help with increasing the performance: 2 Gbps WAN/LAN NAT Routing on ramips MT7621 devices
Since my usecase is set on Wireguard for all clients, those high-level performance settings/tweaks don't fall into my work with this device.
The "special" stuff I am running is basically a self written policy-based-routing for streaming, a timeclock feature for the wifi and that's it.