Had issues with WG tunnel between two RB5009s documented here:
http://forum.mikrotik.com/t/disappointing-wireguard-performance/181394/1
TLDR; CPU frequency scaling was playing havoc with performance until I set both to run at 1.4Ghz
With regards to hardware offloading - if you are going to have multiple tunnels then it’s probably best to go with IPSEC over Wireguard because just one WG tunnel will hammer the CPU even under optimal conditions.