How to connect CKEDITOR correctly?

Question

JavaScript

I recently installed ckeditor editor on my site.
Actually, the connection itself.

<textarea id="test"></textarea>
<script src="../js/ckeditor/ckeditor.js"></script>
<script type="text/javascript">
CKEDITOR.replace('test');
</script>

And here a few questions arose:
1. by clicking on the "Source" function (write code), writing there, for example, div style=".... after switching, what I wrote in the div disappears, like the div itself;
2. Not all styles are connected - buttons without rounded borders, no grayish tint in the navigation block
3. After a long use it slows down terribly (although the computer is quite powerful)
Tell me who knows about these issues.

Answer 1

1. do not click on the functions, there are buttons for this. All editors have code cleaning and tag replacement, all this can be configured, read the documentation for the plugin and everything will become clear. I would even give a link, but you did not even specify the version of the plugin. So...
2. see the console if there are any errors, see the styles, maybe something overrides. According to your description - only Vanga to call.
3. Computer slows down? Is ckeditor slow? The page on which it is connected slows down? How long is this?