I can’t seem to find a good reference on optimizing the Linux Bridge device, I’m working from memory…
Besides verifying the STP (Spanning Tree Protocol) should be off, I seem to remember that by default there is a “Bridge Forward Delay” configured with a value which is desirable for heavy multi-Guest use. If you’re running only maybe 3 or so Guests at most simultaneously, this should be changed
BRIDGE_FORWARDDELAY=‘0’
IIRC these two are the critical settings you need to configure for a <small> network without a heavy, continuous and concurrent networking load.
And, as for your Guests, try both using and not using virtio NIC drivers. There is some discussion whether they’re actually better so try both.
TSU