We can achieve 4.2 Billion routes provided the parameters are set correct.
Step 1 : Understanding the prefix distribution with larger network counts
> We can't have 4.2 Billion prefixes of /24 with IPv4
> At 64k updates MAX, it will take a minimum of 64K BGP updates to advertise all the prefixes
> This is a good practice when advertising IPv6 prefixes too
Step 2 : Set Performance Mode and BGP Options
> Enable BGP Route Packing
> Disable 'View Routes' and 'Route Refresh'
Step 3 : Generate the right kind of prefixes, may import internet routes as well
> Make sure to set the right prefix length