Then why do Android Apps in AD not suffer any kind of performance penalty and work nominally, but Sailfish apps the opposite (and UT not).

No your experience is not. Everyone's is the same.

I see we're back to pretending that major problems do not exist. I seem to recall you were party to the original discussions about this, and had no answer for it then, and don't now.

@MartinK

Ubuntu Touch's UI needs serious work. That's slow / stuttery. Native apps, or more particularly the browser are very quick and make proper use of all available resources - moreso than in Android, vastly more so than SF.