I am planing to add mikrotik where Router 1 is shown on the picture, at this moment i have a switch connected there. Doesn’t a dummy switch broadcast on all ports and thus slows down everything.
What are you thoughts on adding mikrotik there and how would you configure it.
My plan is to optimize wifi CPE bridge connections so that they don’t talk to other mikrotiks on other CPE bridges.
Default configuration works and all PCs have internet access, but i would like to speed things up by a notch and prevent routers 2,3,4 to communicate and send unnecessary data to eachother, they should only communicate with main router through newly added router 1.

Why not use vlans on the main router, and then you have separation by vlan and firewall rules on main router.
A managed switch would then be a reasonable choice instead of the MT device.