How to create a light-weight relational database in R

I've used SQLite function dbWriteTable() in order to create a database composed by a group of 15 tables. Each table has a lot of data, the dimensions of each are (80000, 120) so it's not surprising that the resulting '.sqlite' file is heavy: 1.3 GB. But when saving the files using 'save' function in R, each table has 7.5 MB size. So the total size of the group of R files is under 150 MB. I wonder if there is a way to create a lighter-weight database in SQLite or reduce the size of the database file.