Yeehaw! One of the biggest concerns I've had with Linux KVM (qemu-whatever-whatever) was the some of the latency in disk and network I/O. But in EL 6.4 and I imagine some of the updates to EL 6.3 there have been some remarkable improvements. I don't have any benchmarks for you all, this is more of a 'it just feels sexier' moment.
Yes, I said sexier.. god dammit, I need more of a social life, eh?
As most of you already know, when you look at your memory statistics in Linux, much of your RAM is 'cached'. This is normal and a behavior that enhances the overall performance of your system. But sometimes for the sake of OCD, you may want to flush your system's memory cache to get a better perspective of what's /really/ 'free'.