[Milhouse]

between  updates 605 and 606 the wifi network throughput seemed to go from averaging 2.6 Mhz down load to 1.1Mhz down.  it has been the same on each build since.

There are no changes in #0605 that might affect WiFi performance, and #0606 did receive a new kernel which could possibly be a factor. Can you confirm the first build with degraded WiFi performance?

Are you sure it's not just a change in your local WiFi environment, eg. a new noisy neighbour on the same channel as you? Does changing the channel on your access point have any effect?

I am on a RPi3

RPi3B or RPi3B+? The RPi3B WiFi antennae isn't the best, and it may not take much to reduce throughput. The RPi3B+ antennae, and signal, is much better.