Use 11g parameters...
Try using the 11g parameters, add/change or remove the following:
Code:
db_cache_size #<= Remove
db_writer_processes 1
disk_asynch_io TRUE
filesystemio_options SETALL
memory_max_target 2400M #<= Max memory...
memory_target 2000M #<= SGA 1G + PGA 0.5G + Extra
pga_aggregate_target #<= Remove
sga_max_size #<= Remove
shared_pool_size #<= Remove
sort_area_retained_size #<= Remove
sort_area_size #<= Remove

PS: Allocate as much memory as possible.
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"The person who says it cannot be done should not interrupt the person doing it." --Chinese Proverb