Yes, my experience also always was, that while the pure Tcl code performance isn't great, most Tcl programs perform very well, due to the low resource consumption and overhead.
It doesn't help that Google did a pretty lousy job with Dalvik.
If those tablets were running something like Aicas Java runtime, it would be much different.
Re:Espresso Machine Powered by Tcl/Tk
by johnbuckman on Wednesday July 31, 2019 @07:51AM
(#20573549)
"Androwish", which is Tcl/Tk ported to Android, runs mostly on the C layer sitting on top of Linux. As such, it's way more "performant" than Java.
Its focus on asynchronous programming, rather than relying on threads, really helps, as does the small memory footprint (105mb of RAM used for my app).
Java-based apps on the same tablet that I supply with the espresso machine run at a crawl, whereas my Tcl app feels normal.