Speculative Execution

Speculative execution is a performance optimization technique where a processor performs tasks that may not be needed, based on a guess about future program flow. If the guess is correct, the system gains a significant speed advantage by having the results ready in advance.

If the guess is incorrect, the work is discarded and the system reverts to the correct path. This technique is often paired with branch prediction to keep the processor busy during periods where the outcome of a logical test is uncertain.

While powerful, speculative execution has been at the center of several security vulnerabilities in modern processors, highlighting the tension between raw performance and system security in financial infrastructure.