In practice, whether memory lookup is constant time or log time depends on your access pattern. The TLB makes random lookups more expensive. See for example<p><a href="https:&#x2F;&#x2F;people.mpi-inf.mpg.de&#x2F;~tojot&#x2F;papers&#x2F;TowardBetterComputationModelsForModernMachines.pdf" rel="nofollow">https:&#x2F;&#x2F;people.mpi-inf.mpg.de&#x2F;~tojot&#x2F;papers&#x2F;TowardBetterComp...</a>