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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

#21

Post by McDyver »

ChuckNorris89 wrote: post #13
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.

If you are privacy-minded, KDE (with the kuserfeedback) should put you off, due to the user data it collects and sends back. You can disable the sending back, but not the collection.

There are a number of packets that depend on this, so you can't just remove it. Although you can recompile it to disable data collection, it's not something everyone just does.

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

#22

Post by joezydeco »

CarVac wrote: post #19
joezydeco wrote: post #14

Earlier quoted context omitted.

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.

Here's a fun test when you get a High-DPI screen for testing: hook two screens to Windows, one high and one low-DPI. Then drag the Qt app from one window to the other.

Virtualbox's windows GUI is Qt and shows the problem pretty easily.

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

#23

Post by Closi »

tssge wrote: post #20

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.

Eh, I don't think it's always obvious - for instance Visual Studio Code I would never have guessed was an Electron app.

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

#25

Post by jcelerier »

webmobdev wrote: post #11

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 d…

> 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).

In the end it does not matter that you push pixels from qt5gui.dll or shell32.dll, no ?

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

#26

Post by pjmlp »

yissp wrote: post #16
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?

Qt 6 has moved away from OpenGL.

Now they do like game engines and use the native 3D APIs from each platform.

Which is to say DirectX on Windows and it is quite smooth.

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

#27

Post by notriskfree »

Tajnymag wrote: post #18

Is it bad that I thought of QT as a native UI framework?

If you mainly use Linux that would be a reasonable point of view to take.

However it runs in many environments so it is more like 'a cross platform framework'

It is native code, so in that sense it also native.

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

#28

Post by jcelerier »

Closi wrote: post #23
tssge wrote: post #20

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.

Eh, I don't think it's always obvious - for instance Visual Studio Code I would never have guessed was an Electron app.

When comparing on my machine, VSCode has much more latency than Qt apps for e.g. selecting text, reprocessing syntax coloration..

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

#29

Post by ChuckNorris89 »

McDyver wrote: post #21
ChuckNorris89 wrote: post #13

Earlier quoted context omitted.

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.

If you are privacy-minded, KDE (with the kuserfeedback) should put you off, due to the user data it collects and sends back. You can disable the sending back, but not the collection. There are a number of packets that depend on this, so you can't just remove it. Although you can recompile it to disable data collection, it's not something everyone just does.

This is the first time I'm hearing about this. Do you have a source?

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

#30

Post by CarVac »

pjmlp wrote: post #24
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.

Qt 6 is quite smooth.

I'm patiently waiting for it to become available in open-source repositories.

I may need to set up some other way to use it for my builds…

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