Patch 101969-05 broke TCP/IP throughput. You need to backout this patch or obsolete it with the kernel jumbo patch (101945-27 or later). The latter is recommended.
On Solaris 2.4 x86, later kernel jumbo patches (101946-29) triggered bugs in some of the ethernet cards. This manifests itself as extremely poor TCP throughput. On such systems, you need to install DU10 or later.