First stack transition lags

[Philippe]

In some elementary OS apps, the first "changing tabs" sliding-to-the-side animation lags.
This happens in Appcenter when changing from categories to updates for the first time.
It also happens in System settings the first time you click on each category.

Example:
in system settings, click on "keyboard". The slide-to-left animation lags. Then click "all setings" to go back and on "keyboard" again. The animation is now as it should be.

[Zisu Andrei (matzipan)]

I can confirm this is the case in both applications, although I doubt it has anything to do with Gala. Might be some blocking request happening after the animation has been triggered.

[Corentin Noël (tintou)]

This depends on your computer efficiency, all the situations you underline here behave correctly at the first time on my machine.

[Zisu Andrei (matzipan)]

@Corentin, any computation which presents the risk of blocking the UI thread (which seems to be the case), needs to be run on a separate thread, or at least in a Vala async/yield.

[Corentin Noël (tintou)]

In this case it's not really computation, it's just loading the images, so loading the UI itself from your hard drive... This is where the line between availability and performance is designed right now, that small lag isn't an issue on modern hird drive and a small one on older ones...

[Zisu Andrei (matzipan)]

I have fairly "modern" hardware: 7200 rpm HDD (home drive) and an SSD (root).

The Photos application presents no stuttering when it's loading a folder full of high-resolution images from the hard-drives, so I'm having a hard time justifying that App Center or Switchboard should.

First load the images or the UI and only when this finishes should it trigger the animation, not do both at the same time.

[Danielle Foré (danrabbit)]

I'm going to mark this as "invalid" for Switchboard. There's no clear single action item that can be taken here in Switchboard. If you can consistently reproduce a lag with a certain plug, please open a report against that plug.

[Zisu Andrei (matzipan)]

I can consistently reproduce this with all the plugs, Dan. And now I'm running fully SSD.

[Danielle Foré (danrabbit)]

I can't reproduce this issue at all on either of my machines. Graphics driver problem?

[Zisu Andrei (matzipan)]

I can still see it in Switchboard. Appcenter is currently segfaulting for me so I can't check right now.

It is extremely subtle. I think to best see it, do a screen grab and compare it side by side at a very slow speed.

First load will always skip a few frames.