I am having issues with NAT. The setup is this:

Router Mikrotik CRS1128G4SIN

symetric 100Mbit internet ---> ether1 -> NAT -> ether8 ->LAN

Speed tested with PC connected directly to internet: 80/90Mbits
Speed tested with the same PC connected to ehter8 (NAT) (disconnected from LAN): 40/45Mbits

The configuration is basic, created with quick set.

All connections are gigabit ethernet working on 1Gb full duplex. Tested also using sfp9 and fiber link to a gigabit switch of LAN: same speeds.

The CPU is 400Mhz and when I do a speed test, the CPU usage goes up to 100%.

The router can't be so slow. .Anybody can tell me what may I be doing wrong please?

Your routing with a switch! The CRS is not designed to route your maxing out the CPU.

Bridge it don't route in a CRS, or use a MT router, CCR, etc

Your routing with a switch! The CRS is not designed to route your maxing out the CPU.

Bridge it don't route in a CRS, or use a MT router, CCR, etc

OK. Thank you. What about RBxxx routers?