If it's WAN-LAN bandwidth, just make sure CTF and FA are on. It's debatable whether it supports FA. Apparently if it says it's on, it's optimal, but the HW doesn't support FA. However, it won't matter. You're getting full performance when it says it's on. They probably just don't care to update the firmware text.
If it's the LAN switch bandwidth, you're probably seeing questions about jumbo frames. That is something only you can do by tweaking it for your network. Out of the box you should be in the 900+ area. If so I'd leave it alone.
Aditionally you'll want to install ASUS Merlin to easily control and turn these features on. You can adjust CTF/FA with ASUS firmware, but there is no direct switch. For example, turning off traffic monitor, turns off CTF.