A modern CPU fills its multi-stage pipeline by guessing, correctly around 95 to 99 percent of the time, which way an if-statement is going to go before it actually knows the answer. That guess is what branch prediction is, the guess going wrong is a pipeline flush that costs 15-20 wasted cycles, and the 2018 discovery that the guess leaves observable side effects even when it's wrong is what Spectre exploits.
Cpu-Architecture
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Branch Prediction -
ARM vs x86 in 2026 The instruction-set wars have a clearer verdict than either camp admits. What Apple Silicon, Graviton, Ampere, and Snapdragon X actually proved about energy per instruction, why the ISA matters far less than the business model around it, the legacy-software tax, and the honest case for each architecture across phones, laptops, servers, and the cloud.