Vlan speed and inter-vlan routing killing cpu

RouterOS General
1

SCENARIO:

Problem:
All connections in diagram (included VMware virtual switching system) are 1Gbps, iperf3 server mode running on each Virtual Machine inside ESXi, iperf3 client mode running on PC1
PC1 to VM1-3 reports almost 1Gb bandwidth
PC1 to VM4 (vlan10 to vlan100 routing) reports almost 100Mb bandwidth
While testing bandwidth with inter-vlan routing, CRS125 cpu goes to 100% , could this be considered correct ??
Thinking the routing bottleneck was the issue, I tested bandwidth between PC5 and VM4 (same vlan 100): CPU stays at 5-10% but bandwidth still close to 100Mb

I tried to swap virtual machines as well PCs (if machine performance was involved) , same results .
I can’t figure if the problem resides on routerboard or ESXi (or something else ?)

Any hint in troubleshooting please ?

2

The diagram is missing.
But it is very important to note that the CRS series is NOT a wirespeed L3 router like the switches from competitors!!!
It is only wirespeed (hardware-assisted) on switching, NOT on L3 routing!
So it is normal to see that vlan-to-vlan routing is limited to speeds like 100 Mbps, depending on firewall rules, fastpath/fasttrack configuration, etc.
Switching can be wirespeed when you configure it correctly.

3

Oops.. Image should be ok

Please note that PC5 and VM4 reside on the same Vlan and routing doesn’t take part (as cpu load tells)
That sounds strange to me…

All ports (VMs, ESXi host SW and HW, Routerboard, PCs) status show 1GB
Test to VM4 never exceeds 96-98Mbps.