Although most QB queries are super fast due to simple queries and indexes theres one db query that's extremely slow compared to others:
MonProxy-SQL-PreparedStatement: /* from Build where status = :status */ select build0_.QB_ID as QB1_?_, build0_.QB_BEGIN_DATE as QB2_?_, build0_.QB_CANCELLER_ID as QB13_?_, build0_.QB_CONFIGURATION_ID as QB14_?_, build0_.QB_DESCRIPTION as QB3_?_, build0_.QB_DURATION as QB4_?_, build0_.QB_ERROR_MESSAGE as QB5_?_, build0_.QB_PROMOTED_FROM_ID as QB15_?_, build0_.QB_REPOSITORY_RUNTIMES as QB6_?_, build0_.QB_REQUESTER_ID as QB16_?_, build0_.QB_SCHEDULED as QB7_?_, build0_.QB_STATUS as QB8_?_, build0_.QB_STATUS_DATE as QB9_?_, build0_.QB_STEP_RUNTIMES as QB10_?_, build0_.QB_VARIABLE_VALUES as QB11_?_, build0_.QB_VERSION as QB12_?_ from QB_BUILD build0_ where build0_.QB_STATUS=?

113086 ms last time. It seems that it's required just once during startup and isn't therefore so important but in higher load systems downtime is quite important.