Yay! I finally got to see what the over-temperature warning looks like on my 3B
CPU usage was around 78-86% when idling for me which is less than what mikerr reported earlier, and it feels a little less sluggish than what I recall. That compares with 0% when idling and 20%-30% when dragging blocks in the Pi's Scratch 2 off-line editor.
Not sure if one is meant to be able to run programs in the on-line version but clicking on the green flag did not seem to work for me.
I'm not convinced a complete switch to Scratch 3 on the 2nd of January 2019 for the on-line editor is the right move. Not having details for Extensions yet, with details of how to create and deploy Unofficial Extensions only arriving "later in 2019", is going to prove problematic for some people, users and developers.
It is still not clear what off-line editors will be available beyond, "In the second half of 2019 we’ll also release an offline version of Scratch for Chromebooks".
I note micro:bit and Lego Mindstorms EV3 are included as official extensions, and Lego WeDo 2.0 is "coming soon", but no mention of Raspberry Pi.
Does anyone know what the plans are or the roadmap is for Scratch on a Pi ?