Eliminate sanitizeExit overhead

Editor assessment

The subject states the optimization exactly: the sanitizeExit overhead in benchmarks is eliminated. Type fix is defensible for removing measurement distortion, scope bench is accurate, and the affected mechanism is named. No body quantifies the overhead or describes the approach, a small gap for a performance claim. No footers beyond the PR number. Hygiene is clean. A precise, complete message for a contained benchmarking improvement.