database performance tuning: prefer light-weight IPC over heavy-duty transactions, following bf377e10ff3b;

tuned;

tuned whitespace;

proper system option, instead of hardwired default;

tuned signature: fewer warnings in IntelliJ IDEA;

tuned comments;

clarified build schedule host: proper module;

remove unused dummy;

tuned;

use timeout as default build time predictor if no data is available;