More about programming than computer science, but it does talk a lot about and show some custom algorithms (it's more about programming-in-the-small, though it does talk about some big picture too), also it is old and out of print (last I checked), but I thought it was really good when I bought and read it, so mentioning it:

Writing Efficient Programs

Also has a great bunch of "war stories" about performance tuning in real-life, including one in which people, IIRC, improve the performance of quicksort on a supercomputer by 1 million times or some such, by working on tuning as well as architecture and algorithms at several levels of the stack, from the hardware on upwards.

by:

https://en.wikipedia.org/wiki/Jon_Bentley_(computer_scientis...

Edited to change Wikipedia URL to more specific one.