Quantal has 3.6. I feel that the new version is heavier - at least for my specs. (Beside having this problem).
How could I install an older version of LibreOffice?
I haven't done this, but you should be able to
1) uninstall the current version using Ubuntu Software center or
2) Then go to http://www.libreoffice.org/download/?nodetect or http://archive.services.openoffice.org/pub/openoffice-archive/stable/ for old versions of openoffice and download the .deb package for your environment.
3) Then install using