Haswell is a logical extension of the microarchtectural improvements Intel first introduced in Sandy Bridge. The new chip adds support for Intel’s second-generation Advanced Vector eXtensions (AVX2), which doubles the core’s peak FPU throughput. L1 and L2 bandwidth have been doubled to ensure the execution units stay fed, and the integer and FPU register files have all been enlarged. Branch prediction efficiency also gets a boost. Haswell’s real-world single-threaded performance in unoptimized code is expected to improve by 10-15%. In optimized, AVX2 code, the leap will be much larger; AVX2 includes support for integer vectorization that AVX lacks.

The increased FPU capability and additional AVX2 functionality make a huge difference in Haswell’s floating-point performance. The CPU is capable of up to 32 single-precision and 16 double-precision floating point operations per core. That’s twice what Sandy Bridge could achieve; a theoretical eight-core Haswell clocked at 3.8GHz will offer 972.8 gigaflops of SP and 486.4 gigaflops of DP performance.