Speculative execution is a technique used by modern CPUs to speed up performance. The CPU may execute certain tasks ahead of time, “speculating” that they will be needed. If the tasks are required, a speed-up is achieved, because the work is already complete.

Speculative execution can provide a significant increase in performance, but has been shown to endanger the security of privileged data in some CPUs. For example, the Meltdown security vulnerability affects some Intel CPUs due to a flaw in their speculative execution.

CPU terms

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