Right so I tested a few things
my in work game on my surface pro i5 8gb (they have integrated graphics)
(note. already established chrome janky during preview)
1) uploaded as HTML to a free hosting site.
a) on chrome (hosted , not previewed)
NICE - minimal jank to the point where I would not care about it. there was a little stuttering when my open project in another tab went to auto save but other than im impressed.
b) on edge .......(hosted and previewed)
AWFUL AWFUL OMG 24 FPS janking and stuttering all over the shop
2) packed up nwjs
VERY SMOOTH, fixed 60 fps all they way , 1 tini jank a minute maybe but almost unnoticeable.
So Ashley I think, the return of the janking is just in C3 preview, probably an effect of running the editor and preview in the same browser and my setup/specs.
but .... and big smelly butt.
What happened to edge ??????
Before Christmas , in C2 , my game was performing much better in EDGE than Chrome
but now , previewed/compiled with C3 is performing very badly in edge like less than 30 fps vs 60 fps chrome , and I pretty much haven't changed anything.
(I had not tested in edge recently cos C3 in the browser using chrome etc)
i will check with some older builds to make sure but ....