Editing NetBurst (section)

=== Rapid Execution Engine ===
With this technology, the two [[arithmetic logic unit]]s (ALUs) in the core of the CPU are double-pumped, meaning that they actually operate at twice the core clock frequency. For example, in a 3.8&nbsp;GHz processor, the ALUs will effectively be operating at 7.6&nbsp;GHz. The reason behind this is to generally make up for the low IPC count; additionally this considerably enhances the integer performance of the CPU. Intel also replaced the high-speed [[barrel shifter]] with a shift/rotate execution unit that operates at the same frequency as the CPU core. The downside is that certain instructions are now much slower (relatively and absolutely) than before, making optimization for multiple target CPUs difficult. An example is shift and rotate operations, which suffer from the lack of a barrel shifter which was present on every x86 CPU beginning with the i386, including the main competitor processor, [[Athlon]].