HVM is more performant in PV in most situations with modern virtualization technology. PV drivers on HVM have been a thing for a while now, so your IO and netw

HVM is more performant in PV in most situations with modern virtualization technology. PV drivers on HVM have been a thing for a while now, so your IO and network go through PV even with an HVM instance. SRIOV/"Enhanced Networking" is even better than PV networking drivers, so HVM has another win there if you have NICs that support it (The larger Amazon instances do) PV is significantly slower with system calls than HVM on 64bit hardware, as the x86_64 spec removed two of the four CPU protection rings, one of which being where PV lived in 32bit architectures, below the guest, allowing it to 'intercept' these system calls. Now since it shares a ring with the guest, it cannot intercept these and you are left with doubling the amount of context switches that you were previously. Virtualization extensions from Intel and AMD allow HVM to bypass this and skip the context switch. Other hardware advantages like EPT also give HVM an edge when it comes to memory related performance. About the only area where PV is still better from a performance standpoint is interrupts/timers