When listing approaches, people should look at Skia Compute[0]. While it is true that traditional GPU's are not a super-great match for 2D graphics, modern GPU's are becoming more and more CPU-like, just with more parallelism. I haven't done careful quantitative evaluation of compute myself, but don't feel that any understanding of modern 2D graphics performance would be complete without that.

[0]: https://github.com/google/skia/tree/master/src/compute/skc