As I've already explained, using the Mozilla file browser by default would be the wrong
choice. For most users the GTK+ file browser is used infrequently and works more or less
instantaneously. Almost no one would even notice a three order of magnitude performance
improvement in an number that's nearly zero. But they most certainly *would* notice and
suffer from a file browser that's inconsistent with the rest of their working environment.
Cognitive resources are much more important than the computational kind, so doing what you ask
for would be a serious usability mistake.
Now, you may have some unusual usage pattern that makes you particularly sensitive to file
browser performance. Go ahead and switch to the built-in file browser if that helps. Better
yet, find the bug in the GTK+ file browser and submit patches. But don't burden everyone else
with poor usability just to satisfy your absurd obsession with a boring corner case.
No, I don't want your resume. That would be even less convincing than your chest thumping
about "18 years" of writing software. Whatever your experience you've somehow managed to
avoid mastering enough of the fundamentals to understand why breaking printing functionality
for one user out of millions in a release *candidate* that delivers major performance
improvements and new features is not a catastrophe.