Some optimizations might only apply to certain inputs that are used by benchmarking software. Or the driver makes unfavorable power tradeoffs to maximize performance when a benchmark is running. For example, if the driver knows a benchmark is single threaded, it can artificially throttle other cores and boost the core the benchmark is running on. There's more extreme stuff like GPU drivers replacing shaders (benchmarks don't care about graphics quality) or pre-rendering frames. https://videocardz.com/74912/professional-overclocker-demons...