It matters most for people doing 10-100gbps throughput, CPU usage will be lower and more stable in all cases though.
There has been a lot of improvement to many network card drivers in 11, and I am helping to push/fund the final integration of Matt Macy's "iflib" for the common intel em/igb/ixgbe drivers.
There are a lot of goodput improvements coming soon, which will affect all TCP users. I had Matt Macy upgrade TCP CUBIC to match 2016 RFC and most Linux behaviors (HyStart). Hiren Panchasara has been working full time for almost 2 years to address many other goodput and correctness issues in the TCP stack. Some of these are in 11, but the majority will hit in 11.1.
Another company is working on the recently announced BBR congestion control from Google and a TCP stack with RACK/PRR https://wiki.freebsd.org/DevSummit/201606/Transport. The end result of all this will be a more tightly integrated and coherent TCP implementation, which should make FreeBSD have the best network stack again in 2017 after falling behind for a while.
For your average home / small business user? Or do you need to be at Netflix scale to see the benefits? (that's not a bad thing).