https://github.com/flutter/flutter/issues/59327
This has been a long-standing issue that has completely ruled out Flutter for us. E.g, the Flutterfolio idle login screen uses 14% CPU on my Mac. For a while it sounded like Google was saying that it can't be fixed. But I think they have done some work to address this issue. I'll be very interested in finding out whether it has been fixed in Flutter 3.
Reading the bug report my takeaways were the following:
1. Here is a specific issue we ran into which to be fair is unacceptable in terms of perf but a blinking cursor in an otherwise idle application has crazy high CPU usage numbers trying to run the animations associated with the blinking cursor.
2. They tried the same thing on Linux and CPU usage was 0% so already it appears this is more of a specific mac bug rather than some general widespread thing.
3. Further in the thread a number of potential solutions get mentioned and were under development including just writing a custom shader to handle the blinking cursor (so a solution looks possible)
They just made Mac desktop support stable as of less than 24 hours ago for the first time. None of this strikes me as that egregious. A whole number of major perf improvements have landed since then and it's not even clear if this is still an active problem in Flutter 3.
I think trying to extrapolate this one bug into some widespread disaster scenario is a mistake.
The question in my mind is whether Flutter is consistently and significantly more resource efficient than web technologies for my particular use cases.
While I understand this may be a dealbreaker issue for your use-case, we've been pretty busy getting a few higher-priority (overall) issues fixed (universal binary support, CJK text input, key event APIs, etc.) prior to 3.0, but we'll get to this.