Database schema design help needed
You should use one table per object of interest.  That means one table for users, one table for pages, one table for posts, etc.  Use a normalized database (See database normalization) for transactional data.  This is precisely what relational database management systems are built to do.  Don't presume you are going to have performance problems because you have many rows.  Most systems perform better with many rows than with just a few.