Breaking the 100G mark on ROSv7.1rc4 in our lab…
What are the traffic patterns you pushed through it ?
IMIX ? Constant values ? Always 1500 bytes ? 64 bytes ?
Now imagine CHR with a FastPath implementation 
By the way keep in mind that,
Fast Path is supported since RouterOS v7 for "vmxnet3" and "virtio-net" adapters.
https://help.mikrotik.com/docs/pages/viewpage.action?pageId=18350234