If you would use a conditional jump, that would have a high cost.
However the maximum or minimum should always be computed without conditional jumps and many CPUs have special instructions for max and min, which are not more expensive than additions or subtractions.
On CPUs without max & min instructions, computing max or min requires 2 instructions (compare + conditional copy).
2 instructions vs. 1 instruction increases the program size but not necessarily the execution time, if the instructions can be overlapped with others.
Due to the complex architecture of modern CPUs, it is impossible to determine the cost of a simple sequence of instructions in the general case.
For each particular CPU, a different but equivalent sequence of instructions can be the best and longer sequences of instructions may happen to be executed in less time, if they can be better overlapped on a certain CPU.
