I am interested in methods of 2d and 3d rendering using single thread on an average CPU (e.g. for programming games for old and low-end PCs).
While I usually have no performance problems when using OpenGL and shaders, I have little understanding about how can real-time 3d, lighting or certain effects (like blur, other convolutions or perspective transformations) be achieved and made fast enough without using GPU.
I am aware of some obvious optimization techniques (precalculating functions, rendering in lower resolution and then stretching, calculating convolutions for each axis separately), but they often do not give enough performance for my applications.
Are there any sources (or keywords for Google) where I can find out about platform-independent rendering optimiztions and algorithms for CPU?