I am curious about the new laptop chips from Intel. I think I will wait and see what the laptops look like.
If you're looking for a bigger iMember, an SSD would give much more of a performance gain than a new chip IMO.
Although your machine is 4 years old and Apple tends to put them out to pasture regarding OS upgrades from 5 - 6 years old.
See what the new ones bring for sure if you can wait.
I get to live vicariously through the new equipment I install for my customers, and the current SSD laptops I can't even come up with words for regarding how fast they are. I have had the chance to experience pretty much all processor/machine upgrades over the last 20 years, and I have never seen such a quantum jump in performance as when SSDs were put into these machines. IMO it is going to take a few years and one hell of a chip upgrade/standard HD combo to equal the speed of any current or recent past machines with an SSD.
If you can afford it, you only go around once.