In 2.0 we've set a number of things by default to work better and use all the capacity with no need for tweaking. Just doing this will start a proxy on all CPU cores, support both H1 and H2 and will automatically enable round robin load-balancing, tune the maxconns, something which used to be a hassle in previous versions, and enable connection pooling and reuse by default:
listen foo
bind :80
mode http
server www1 192.168.1.1:80
server www2 192.168.1.2:80
server www3 192.168.1.3:80