CXPACKET waits are due to parallelism where the query optimizer decides to break up the IO and processing for a query into multiple threads that run concurrently then it gathers the data back together to provide the necessary output. In pretty much every case, the CPUs wait for IO streams because the IO subsystem is slow as molasses in February, relatively speaking. 😀 So by providing better IO capabilities you can feed those GHz-speed CPUs with data with fewer waits --> much faster parallel query performance. This is the 10000 foot view, btw. There is just a weeeee bit more to it than this. 😎