Haswell vs Broadwell is a very incremental change. Pick any metric you like and it'll be better by at most 10 percent. In most practical metrics it's a lot less than that.
Come this Friday, the same CPUs have been shipping in the 15" retina MacBook Pros for 2 years. Last spec bump was May 2015, but the change to Haswell processors was in late July 2014.
Come this Friday, the same CPUs have been shipping in the 15" retina MacBook Pros for 2 years. Last spec bump was May 2015, but the change to Haswell processors was in late July 2014.