I understand completely. I am tuning for a specific application, namely windows 7 machine to a linux samba server. Since I am using it for media storage I am testing sequential access only.
The biggest improvement came just from software configuration enabling smb2 protocol. Testing at 9014 packet size saw reduced performance, but it appears 4088 is faster in some tests that the default 1500.
Either way, if the configuration page is not some hidden feature, it should be exposed in router mode and AP mode I'd think.