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Even with old_snapshot_threshold = -1 (which disables the "snapshot too old" feature), performance regressions were seen at moderate to high concurrency. For example, a one-socket, four-core system running 200 connections at saturation could see up to a 2.3% regression, with larger regressions possible on NUMA machines. By inlining the early (smaller, faster) tests in the TestForOldSnapshot() function, the i7 case dropped to a 0.2% regression, which could easily just be noise, and is clearly an improvement. Further testing will show whether more is needed.