Thank you for writing in, you're using PRO. Don't worry about the
/x/ path, that is just a default for X and PRO. You can actually change that under PRO > Settings > Custom Path.
That does not have anything to do with your site performance, maybe it is your connection or a plugin you just installed recently causing your site to be slow.
You can follow some of the Performance improvements guides provided here, but I advise that you only do this after you have finished developing the site, as sometimes caching can make your changes not to take effect immediately.