How to keep an Oracle 11g instance lean? As a Mac user I run a local Oracle Enterprise Linux (OEL) Developer Day VM that houses an Oracle 11g instance for development/unit testing.  I frequently refresh the data in the schemas (sometimes multiple times a day) and do not have a need for snapshots or backups.  The number of rows in each schema's tables are orders of magnitude smaller than those of a production instance.

I've had to extend the tablespaces' size more than a few times and I suspect I have improper resource allocation to begin with (SGA, PGA) for the way in which I'm using the instance.  I have a similar concern about my sizing/configuration of the VM itself since I'm only using it to house the instance, not for SQL Developer, TimesTen, etc..

I'm looking for recommendations/resources to help me 


Optimize my database instance for a small amount of data in the first place
'Clean' my database instance so that I don't need to increase data file size
Modify my OEL VM to most efficiently run the only thing I
need it to run -- the Oracle instance


For example, I have turned off snapshot collection.  But I think there are other (more?) impactful changes I can make to help increase the performance and reduce the footprint of VM.
The best check for memory allocations is the buffer advisories. These estimate the impact on caching effectiveness of modifying the cache sizes, so you know whether you have the sizes of the PGA and SGA correct, and whether reallocating memory from one to another would be beneficial.