Not sure, but based on what I'm getting / seeing, I'm not receiving a full routing table.Does your Transit ISP send you full route?
Even if I accept the whole bgp-in without any discard or deny rul, the only route I am getting is 0.0.0.0/0
I looked and on 25 firewall rules it caps at 836 mbps.Check https://mikrotik.com/product/RB3011UiAS ... estresults you will see that RB3011 can do 1Gbps but of course it will depend how you use it.
So by default L2TP routes all traffic through the VPN?By adding routes manually on your PC, not to route specific networks over the tunnel.