Deliverator
Graphical Hackificator
I tried the original UnitPanel.lua code fix by @Deliverator and it eliminated the lag BUT it removed builder improvement options from the UI. I could move builders but there were no icons for build farm, mine, etc, rendering them useless.
Huh. That definitely wasn't happening the latest time I tried it. Anyway, there is a slim possibility that the September 2019 patch will actually resolve this.