why choose a managed switch instead of a router?

I am planning to segment my network into 3 vlans: main network, one vlan for cameras, one vlan for smart tvs, tv boxes, etc..

I need restricted controlled communication between the vlans

In my country, routers are cheaper than managed switches especially L3 switches (which if I understand correctly, I need L3 switch for vlan communications between them)

I read the advantages of managed switches over routers are:

1. they are faster
2. they have more ports

My questions are:

1. how much faster are managed switches; is this something noticeable?
2. I can get more ports by using cheap unmanaged switches connected to the router
3. are managed switches more efficient; consumes less energy?
4. are manages switches more reliable than routers; less prone to freezing or needed restarts?

Routers offer additional features like wireless AP, guest WIFI, etc...