AWR Report - Tuning Database
It appears that something like 95% of your wait time is on CPU.  Even if you completely eliminated the direct path reads, you'd eliminate less than 2% of your total wait time.  It seems unlikely that a 2% reduction in your wait time would even register as an improvement.

Taking a look at what is consuming all that CPU-- you have a handful of very CPU intensive queries. 0dp0c8wux0jnt and 3g2kw67v3v0qs are consuming 60% of the CPU your system is using. Have you looked at optimizing those queries so that they use less CPU? 3g2kw67v3v0qs in particular takes nearly 5 seconds per execution.

What else do you have running on this machine?  A total SGA &amp; PGA that is 6% of the memory available on the machine implies that you probably have a number of other things running (perhaps many database instances).