[fizzynut]

If everything you do stays in the rails of QT you're going to be fine. But you try to do something simple like load a 2GB file and everything starts to fall to pieces, then you're going to assume the people that wrote this are super clever and that a 2GB file is too complicated, too niche, too hard of a problem, it needs to be "highly optimised", etc.

The reality is QT/whatever program/framework is doing 100 things you don't care about when loading/rendering a file. If we only care about 1 thing we can do that much better because we don't care about the 100 other things our naïve code we wrote in 5 minutes outperforms the standard element by a factor of 1,000.