When the full process is performed on the tabular database, you are still storing the previous model in memory, so you need at least twice as much memory as it needs during the normal operation.

Two options:

1)Use Process Clear, followed by Process Full – deletes all data from model, before loading it again. Backup database prior to this.

2)Perform incremental Full processing on tables instead of Full on database. Requires a script, example http://www.sqlbi.com/articles/incremental-processing-in-tabular-using-process-add