First I'll describe the hardware. The CPU is an Atom D2700 on the Intel D2700DC board. 1066 MHz DDR3 memory. Two cores hyperthreaded. Running Ubuntu 12.04 Server. Firefox and Chromium packages are stock. Node.js and clang 3.1 are x64 Linux binaries downloaded from their respective websites. Emscripten is commit 26250471b46a68204711f037f33790bfb4ba37c7 in the master branch.
|C++||gcc 4.6.3 -O3||SSE||24040000||1|
|C++||clang 3.1 -O3||SSE||22530000||1.07|
|C++||gcc 4.6.3 -O3||scalar||18730000||1.28|
|C++||clang 3.1 -O3||scalar||13040000||1.84|
Next time I hope to update these benchmarks on a high-end desktop CPU.
As always, if you'd like to reproduce these results or question them, the code is available on my github.