Why 4x? Well, 0.12 just made transaction validation like 7x faster I believe with libsecp256k1. The impact on relay, there are technologies that have been discussed earlier like IBLT and weak blocks. So segwit fixes malleability ,allows more Script upgrades, allows fraud proofs, allows pruning blocks for historical data, improves bandwidth usage for light nodes and historical sync, and it's P2SH compatible for old senders so that non-upgraders can still send funds. This gives us time for IBLT and weak blocks to develop, so that we can see whether the relay and propagation stuff can have time to work.
http://diyhpl.us/wiki/transcripts/scalingbitcoin/hong-kong/segregated-witness-and-its-impact-on-scalability/I think even the worst of the big-blocker-or-bust have to stfu and think before looking very stoopid now.
meritocracy means you don't get a say unless you are the best ... sit down at the back of the bus until you get a clue.