Speedup theorem

In computational complexity theory, a speedup theorem is a theorem that for any algorithm (of a certain class) demonstrates the existence of a more efficient algorithm solving the same problem.

Examples:
 * Linear speedup theorem, that the space and time requirements of a Turing machine solving a decision problem can be reduced by a multiplicative constant factor.
 * Blum's speedup theorem, which provides speedup by any computable function (not just linear, as in the previous theorem).