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Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

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Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#11

Post by webmobdev »

My personal experience in using QT apps is that they load / render perceptibly slower than the native UIs and QT applications are slightly bulkier in size (storage space and memory). This is kind of understandable as QT emulates the UI through its own library (unlike, say, Lazarus IDE / Delphi GUI library that directly use the native UI library). However, size doesn't matter much today, and the very minor rendering delay is hardly discernable and doesn't reduce its usability in any manner. QT is a mature framework and especially suited for C++ developers. It's one of the popular ways open source developers choose to make their software available on multiple platforms.

As for "OS built around QT" you can try it our yourself - KDE Plasma ( https://kde.org/ ) is a GUI for Linux / xBSD that is built with QT, and on the mobile scene, Sailfish OS ( https://sailfishos.org/ ) also chose QT for its OS UI and recommends it for app development on its platform.

All said, often nothing outperforms the native libraries in terms of usability. (Performance, in terms of resource use, is a different matter as there are GUI libraries that are actually lighter on the system than the native ones, and even QT).

Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#12

Post by rvz »

donboscow wrote: post #8
rvz wrote: post #7

Just look at Telegram as a real example and compare that against the other messenger apps since the majority of them use Electron and Telegram uses Qt for some of its desktop clients.

You mean to say Telegram is smoother than other apps? Will try it out. In general, would you say that Qt is supposed to work just as buttery smooth and native on Mac or iPhone as a native app? And will an OS built on Qt like Ubuntu Touch will be as smooth and beautifully craftable as iOS apps on iPhone?

> You mean to say Telegram is smoother than other apps?

If those other apps are using Electron then yes; Telegram is smoother.

> In general, would you say that Qt is supposed to work just as buttery smooth and native on Mac or iPhone as a native app?

Yes. No difference in RAM, Disk, or CPU usage than any other native app.

> And will an OS built on Qt like Ubuntu Touch will be as smooth and beautifully craftable as iOS apps on iPhone?

Yes. One example is AsteriodOS which is an OS for smartwatches built using Qt. [0]

[0] https://asteroidos.org/

Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#13

Post by ChuckNorris89 »

jklinger410 wrote: post #10

Speaking of QT...I've wanted to switch to a QT-based DE for a while but I don't like lxqt or Plasma. It would be really cool if there was another option.

What's wrong with KDE plasma? The beauty (and curse) of Plasma, is that it's so configurable, you can make it look and feel like anything else.

Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#14

Post by joezydeco »

ChuckNorris89 wrote: post #9
CarVac wrote: post #3

In my experience QML is buttery smooth on Linux, even on older hardware, but it just isn't as smooth on Windows.

Yep, that's why KDE is so smooth even on older hardware. But on Windows, some QT apps (GnuPG pinentry-qt for example) often have weird scaling issues where they de-snap and move out of their place.

Qt still hasn't figured out to work with Windows desktop scaling. It's a nightmare on high-DPI displays. I wrestled with this 5 years ago and it's still not fixed.

Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#15

Post by user1846291 »

jklinger410 wrote: post #10

Speaking of QT...I've wanted to switch to a QT-based DE for a while but I don't like lxqt or Plasma. It would be really cool if there was another option.

Try cutefish! It’s somewhat rudimentary still, but looks great, stays out of the way, works great for me

Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#16

Post by yissp »

CarVac wrote: post #3

In my experience QML is buttery smooth on Linux, even on older hardware, but it just isn't as smooth on Windows.

Any idea why? I've heard Windows OpenGL drivers are less performant, especially AMD's, could that be part of the reason?

Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#19

Post by CarVac »

joezydeco wrote: post #14
ChuckNorris89 wrote: post #9

Earlier quoted context omitted.

Yep, that's why KDE is so smooth even on older hardware. But on Windows, some QT apps (GnuPG pinentry-qt for example) often have weird scaling issues where they de-snap and move out of their place.

Qt still hasn't figured out to work with Windows desktop scaling. It's a nightmare on high-DPI displays. I wrestled with this 5 years ago and it's still not fixed.

With QML you can implement native fractional scaling but I don't know how it interacts with Windows's scaling mostly because I don't have a high DPI screen on my Windows computer.

My application has a setting where you can choose whatever arbitrary scale you want, smaller or larger than default.

Re: Ask HN: Smoothness and performance of Qt based systems vs. native apps and OS

#20

Post by tssge »

I find Qt is on par with native apps. Didn't even know it wasn't considered native.

Electron apps on the other hand are very obvious from their resource usage, general laggyness and slow startup time. Say compare Discord (Electron) to Telegram (Qt) and it's like night and day.

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