I have Joomla website with blog on it, but like you know Joomla is not as fast as WordPress, so I created blog in WordPress and add it on subdomain (blog.myjoomlasite.com <- it's only example)

My question is, have someone expreinece with this Joomla or WordPress website and other CMS as subdomain?

Because, after I took backup with akeeba backup component, I got all files including those from subdomain, but database file I got only for Joomla website. I do not even need it for blog, because I can get it over wordpress dashbord.