Computer science is the mathematics behind counting.
You count the number of "swap" operations in insertion sort, quicksort, or merge sort. You count the number of "memory" operations. You count the number of bytes used.
When precise counts are difficult, you learn big-O notation to estimate how counts change as variable grow. Etc. etc. etc.
I would consider what you described to be "algorithms" (or "complexity theory"), a particular sub-area of computer science. There are quite a few other areas of CS.
The ACM organizes a number of SIGs (Special Interest Groups), each with their own (often several) conferences [1]. Some of the more well-known SIGs include SIGPLAN (Programming Languages), SIGGRAPH (Computer Graphics), and SIGLOG (Logic and Computation). What you described probably falls best under SIGACT (Algorithms and Computation Theory).
> the mathematics behind counting.
Traditionally, this is combinatorics, not any particular part of computer science. Complexity theory concerns itself with specifically counting the amount of resources used by a formal process.
Computer science is much more like Mathematics than Physics.
It feels wrong calling "computer science" a science, in the same sense of calling "Mathematics" science.
You count the number of "swap" operations in insertion sort, quicksort, or merge sort. You count the number of "memory" operations. You count the number of bytes used.
When precise counts are difficult, you learn big-O notation to estimate how counts change as variable grow. Etc. etc. etc.