The generic log method in slf4j-jdk14 is missing a wrapper to test if the level is loggable:

if (logger.isLoggable(julLevel)) {

Without it, the stack trace elements are getting created from org.apache.commons.logging.impl.SLF4JLocationAwareLog unconditionally.

I suggest changing this method as follows:

public void log(Marker marker, String callerFQCN, int level, String message,
Throwable t) {
Level julLevel;
switch (level)

{ case LocationAwareLogger.TRACE_INT: julLevel = Level.FINEST; break; case LocationAwareLogger.DEBUG_INT: julLevel = Level.FINE; break; case LocationAwareLogger.INFO_INT: julLevel = Level.INFO; break; case LocationAwareLogger.WARN_INT: julLevel = Level.WARNING; break; case LocationAwareLogger.ERROR_INT: julLevel = Level.SEVERE; break; default: throw new IllegalStateException("Level number " + level + " is not recognized."); }

if (logger.isLoggable(julLevel))

{ log(callerFQCN, julLevel, message, t); }

}