I'm not sure what more information I could provide but here goes:

I'm using the default settings and config as show in the text readme file you provide in the module download here from DNN (1.0.4 as stated).  I do not see detailed info on config options relating to caching of the control (icons, etc.) that might speed up the rendering of the FCK text box control on a page.  It is installed as said and in use, so I don't follow your point about wanting to configure it. 

I guess what you're saying is there are no options to improve loading time as a page is rendered.  I will scour your main site (tienda) in case there are more details or discussions there.  Perhaps I'll reload that distro from your site to see if that is any different (had in place before as well on a 4.0.3 install and did not notice the speed issue). 

Perhaps this can help...
Look at John Mitchell's blog were he writes:

So, for a quick fix and to give your web server a rest, you can place the following code into any skin that you would then apply to any page where you want to allow content to be cached by the people browsing your site.

<script runat="server">
   Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
      'HttpCacheability.Public allows all content to be cached by Proxy servers and client machines.
      Page.Response.Cache.SetCacheability(HttpCacheability.Public)
   End Sub
</script>

Maybe this can help.