Small lag first time plugs are opened

[junocomp]

There's a small lag when clicking any of the settings icons, such as a Desktop, About, Network, etc for the first time. The second/third time you click on the same settings the lag is gone and it works fast.

[cassidyjames]

This looks like it is because each plug is constructed the first time it is opened. I believe this is preferable to constructing every single plug when Switchboard is opened, and this is probably super dependent on hardware. For example, on my i7-5557U with 16 GB RAM it's barely noticeable, though with some plugs like Keyboard and Language & Region it's more noticeable.

[jeremypw]

Still noticeable in the Gtk4 port, resulting in visual glitch at start of animation.