The AFL++ queue only grows and id: numbers increase. Keep the merged profile and the highest replayed id per instance, then replay only new entries on the next run. Hourly coverage tracking of a large campaign will become cheap!
Replay in queue order using the time: field and record which input first covered each line or function, plus a coverage-versus-time curve.
From llvm-cov branch data, list branches where one direction is covered and the other is not, ranked by the uncovered code behind them. These are the most actionable targets for seeds, dictionaries and harness changes! A file, maybe called "frontier.txt", next to gaps.txt.