Doing VLANs properly

Hi, I’m running an edge router with OSPF on RB5009.
There are >30 vlans from various interfaces running OSPF, created as /interface/vlan bound to physical interface - and not to a bridge.

I am curious whether I can improve the CPU load on that edge router by creating one super bridge which would consist of all physical ports and address OSPF Vlans by creating vlan against that bridge. Would it save actually some CPU?

How many router do you have on your network? A diagram would be nice, something like the diagram below.
OSPF2.png

Your description is not clear, a configuration export would have been better. Anyway, if each of your VLAN interfaces is attached to a single underlying interface and you do not bridge traffic from one VLAN interface to another, there is no advantage in inserting a bridge between the physical interface and the VLAN ones currently attached to it directly. If you do bridge VLAN traffic between interfaces, then indeed using a single VLAN-aware bridge would save some CPU.