Hi,
You're bench marking Quagga in its default configuration with a 30s MRAI against BGP implementations that do not implement an MRAI at all. Your convergence time numbers as a result are not apples-apples.
You should configure Quagga with a 0s MRAI (neighbor ... advertisement-interval), or at least some part of your numbers are just indicative of what no-MRAI BGP versus 30s MRAI.