Support Core plugin currently does not record log levels. Since they can be configured independently from Log Recorders, there may be excessively verbose logging set up that slows down Jenkins but doesn't get shown anywhere (Jenkins log is limited to INFO and up). It would help if Support Core captured which loggers are set up, equivalent to the following script console script:

def lm = java.util.logging.LogManager.logManager
lm.loggerNames.each { n ->
  def level = lm.getLogger(n).level
  if (level) {
    println "${n} - ${level}"
  }
}