Amazon announced the availability of C4 instances type, announced since last November.
Interestingly, the new C4 instances are based on a Intel Xeon E5-2666 v3 (code name Haswell) processor custom optimized for EC2, that runs at a base speed of 2.9 GHz, and can achieve clock speeds as high as 3.5 GHz with Intel® Turbo Boost.
There are 5 instance types, ranging from 2 virtual cores (on phisycal with HyperThreading enabled) and 3.75 GB of memory to 36 virtual cores and 60 GB of RAM:
Intel® Xeon® Processor (E5-2666 v3) is based on the Intel Haswell micro architecture that is a notable improvement on its predecessors. It is better at predicting branches and more efficient at prefetching instructions and data. It can also do a better job of taking advantage of opportunities to execute multiple instructions in parallel. This improves performance on integer math and on branches. This new processor also incorporates Intel’s Advanced Vector Extensions 2. AVX2 supports 256-bit integer vectors and can process 32 single precision or 16 double precision floating point operations per cycle.