The In-Portal has built-in ability to track slow database queries on the Front-End. This functionality can be enabled by defining these constants in "/system/debug.php" file:
Once enabled all slow queries from Front-End would be logged into "SlowSqlCapture" database table. The functionality is in beta stage and therefore doesn't have any UI in Admin Console.
A bug was discovered recently, that once enabled a fatal error happens on each slow query logging attempt:
When logging is enabled the "\kDBConnection::Destroy" method should be called prior to "\kApplication::logSlowQuery".