Without knowing what Flutter version Classroom was using before impeller was released and how active development is on Classroom at google its hard to say if they could easily upgrade to the latest version. Flutter has had a lot of breaking changes leading up to the impeller release so it's hard to say if they actually upgraded to the newest version although yeah it is bad that they haven't done it by now if they didn't and if they did upgrade to impeller and it's still slow that's also bad.