And one of the reasons that software like Oracle is so complicated and expensive. Oracle spent years getting the OS kernels out of the way, partially for platform consistency/supportability sake and partially for performance. They obviously still depend on the kernel for a variety of things, but memory management, networking, filesystems, etc. can all be done in Oracle-space at this point.
But what it buys Oracle is not performance, but rather bragging rights for being a little faster at a moment in time.
However 3-6 months later, you'll get comparable performance from improved kernel, CPU and disk speeds. Are those 20% in performance for 6 months worth the premium oracle is charging (which, in part, reflects their harder work)? For most customers most of the time the answer is no.
If you depend on performance, you don't use Oracle in the first place - Vyahu, OneTick, kdb, Vertica are the speed demons (as well as TimesTen which was acquired by Oracle - but is distinct from their "standard" offering)
