Embree

Embree is a collection of high-performance ray tracing kernels, developed at Intel. The target user of Embree are graphics application engineers that want to improve the performance of their application by leveraging the optimized ray tracing kernels of Embree. The kernels are optimized for photo-realistic rendering on the latest IntelĀ® processors with support for SSE, AVX, AVX2, and AVX-512. Embree supports runtime code selection to choose the traversal and build algorithms that best matches the instruction set of your CPU. We recommend using Embree through its API to get the highest benefit from future improvements. Embree is released as Open Source under the Apache 2.0 license.

There is an implementation for Blender from Stefan Werner (Blender, Embree).

Benchmarks:

Embree3

There is our implementation of API Embree v3.0.0 for Blender 2.79: