I'm on FTTN x2 maxing out my connection @ ~40 Mbps and my router's CPU averages a measly 5-10% load (AES-NI enabled). My setup:
-SuperMicro A1SRi-2558F board w/ 128GB SSD & 8 GB RAM in a SC101i case
-pfSense v2.4.4-p1 64-bit (based on FreeBSD) w/ several packages
-PIA VPN client (cipher TLS v1.2 DHE-RSA-AES256-GCM-SHA384, 4096 bit RSA)
-Sonic VPN client (cipher TLS v1.2 ECDHE-RSA-AES256-GCM-SHA384, 2048 bit RSA)
Most of my LAN devices are selectively routed over these VPNs with a few exceptions... You would have no problem handling 75 Mbps+ with a similar setup. Somewhat overkill perhaps but it gives me options when it comes to running packages (Snort, Squid, Apcupsd, etc.). I utilize and appreciate Ubiquiti equipment but found them lacking when it comes to their routers.