Just a couple of observations;
There is no separate "Hifi-Firmware".
Tesla does not do regression testing. QA seems to be the biggest weakness at the company.
We should somewhere start a bug tracker of newly introduced bugs, as this seems to be getting more frequent. Like they introduced the front sensor bug in 2017.42 and took almost 6 months to finally fix.
Now, my observation regarding .16, coming from .12;
Why TF did it take 6 years and the phase out of the hardware to finally optimize the MCU to work somewhat snappy!? OMG what a difference! The interface overall is significantly faster, data transfer speed has increased significantly. Measuring through fast.com, I used to get around 8MBit on good LTE, now I'm seeing 16-18 MBit even on a single bar. Result; my Wifi repeater in the garage is going out, as it results only in about 6-8 MBit thanks to architectural challenges.
And it's not just the browser, the lower latency and better connection speed is especially noticable when using voice control.