It's been interesting seeing the differences between the Mojave betas that Apple has been delivering. The swings in graphics performance for Acorn have been pretty dramatic in ways that I've not seen before in previous OS cycles.

Beta 2: Pretty good. B+

Beta 3: Pretty damn good. Acorn (and Metal in particular) was buttery smooth. A+

Beta 4: Crashy and slow. D-.

Beta 5: Decent. B+

Beta 6: Holy hell brushing is slow as crap what happened? F------

Now I need to spend some time with Instruments and other dev tools.