We released Oracle Solaris 10 1/13 today, and one of the things we mentioned was performance improvements.
On the Oracle Performance and Best Practices blog, there's a discussion of one of those improvements:
"Oracle Solaris 10 1/13 enabling a TCP receive window size up to 1 MB has up to 8 times faster transfer times over the latency range 50 - 200 msec compared to the previous Oracle Solaris 10 8/11."
This improved performance capability was previously introduced in Oracle Solaris 11.