Before any thoughts on your current configuration, you seem to be using the CRS 310 configured as a router, so around 500 Mbps seems to be in the right ballpark for routing without firewall according to tests:
https://mikrotik.com/product/crs310_8g_2s_in#fndtn-testresults
Usually the “reference” to have an idea of real life performance is the “Routing 25 ip filter rules” for 512 bytes packets which is 186.8 for that model, since you have no firewall filter set, you can take the “Routing none (fast path)” line that is 531.3.
This:
/ip dhcp-server network
add address=0.0.0.0/24 dns-server=0.0.0.0 gateway=0.0.0.0 netmask=24
looks however very strange to me, what is this setting for?
It could be an artifact of using Quickset that somehow didn’t work as intended, see:
http://forum.mikrotik.com/t/dhcp-doesnt-deliver-an-address-for-a-gateway/173039/1