Canon C100 aliasing in FCPX

I posted on this a few weeks ago with different footage and encountered the same issue which I can't seem to resolve. I have an interview I shot with the C100. The original footage looks great - looking at the Quicktime file from the Original Media folder. When I bring it into FCPX, there is aliasing which I can see in the subject's glasses - stair stepping (I think that's what it's called) . Her hair likewise comes across as a little noisy. When I optimize the footage, it's all cleaned up - looks just like the QT file. It was suggested I change the Field Dominance Override setting to Progressive. I did that and it didn't make a difference. Only optimizing seems to fix it. I just now exported the unoptimized clip (to Pro Res LT) and it looks fine. So I'm assuming that the aliasing is something I don't need to worry about since it looks good after export. Right? Or should I be concerned over this? I'd rather not generate all these bigger files if I don't need to. thx

Depends on your hardware (mostly the GPU), if you have the preferences set for better quality or better performance, your Mac's screen resolution, and how much it is shrunk down or enlarged in the Viewer.

You're a genius. I checked my preferences which I'd set to Better Performance (which sounded good at the time) and switched it to High Quality. That fixed it. I'll leave it at that setting unless I have playback problems. Thanks!

Definitely, "Better Performance" is good pretty much for rough draft viewing and quick cutting. Always change back to "High Quality" to do any final review on your project.

Soooo many people get caught out by this. Really I think Apple should make the default setting to be best quality. Then if it struggles to play it should ask the user if they'd like to reduce quality in prefs.

That way the user becomes aware of the setting.