OnlyOffice might be a better option here - its UI is similar to MS Office, and it has a much better MS Office file format compatibility compared to LibreOffice.
I've never heard of OnlyOffice, but that really looks quite promising. I'll have a deeper look at it later, but even though it's all webapp based it can't really be slower than libreoffice...
They have desktop apps too, in my machine I'm only using the desktop stuff.