Tell me, please, I have a template with 500k inclusions. What will be faster and more correct - to use TemplateStyles or Common.css?
TemplateStyles vs Common.css: Performance


Depends on your traffic. Common.css will be downloaded on every page, but only once per visitor; TemplateStyles will only be downloaded on pages where it is needed, but every time someone loads the page. if you have millions of pages and the typical visitor only looks at one or two, TemplateStyles is probably faster, if you have not much more than 500k pages or long sessions, Common.css is. Of course, this is just guesswork until you actually measure it.
Overall, I’d expect there is not a huge difference and you should feel free to decide based on different aspects such as which is more convenient for editors / how open do you want it to be to editing.

Hello:) Thanks for your answer. Im talking about Russian Wikipedia, and this template: https://ru.wikipedia.org/wiki/Template:Скрытый_блок