Heavy swap when inserting into a global temporary table from an external table

Hello,

I'm facing a heavy swap issue when trying to insert into a temp table from an external table pointing to a file with about 280000 lines.

I've recently joined this company so I don't know all the details of the server installation/configuration. The information I could gather is:

The server OS is Red Hat Enterprise Linux Server release 5.8, 8 CPUs, 20GB RAM.

There are 9 Oracle 11g instances running on this server, most of them 11.2.0.4 SE.

Instance caging is not in place because of SE, so potentially all the instances can use the 8 CPUs.

The memory allocation for most of the instances is pretty low : 500 Mb for SGA and 100 Mb for the PGA. Some have little bigger than this.