Scala: Fold Left Question

I recently realized that I could make a piece of code I posted in a recent blog much cleaner using foldLeft. I have a bit of a problem however, the code is in a very performance sensitive area and I should break out of the fold whenever I encounter a certain condition. To the best of my knowledge foldLeft has no way to break out. It just folds all the way and you get your result at the finish. This is a bit unfortunate. Is there a way to break out and still keep the code clean?

Here is my example, old code first. A PowerSource is on if any of its incoming power sources are on.

 private def updateOnOff = {
   def calculateOnOff: boolean = {
     incomingPowerSources.foreach( p => {if( p.isOn ) return true; })
     return false;
   }
   val newOnOff = calculateOnOff
   if( cachedOnOffBoolean != newOnOff ){
     cachedOnOffBoolean = newOnOff
     notifyConnections;
   }
 }

Here is the new code using foldLeft.

  private def updateOnOff = {
    val newOnOff = incomingPowerSources.foldLeft( false )(_||_.isOn);
    if( cachedOnOffBoolean != newOnOff ){
      cachedOnOffBoolean = newOnOff
      notifyConnections;
    }
  }

The new code is far nicer than the old code. I've decided I'm going to go with it. In most cases PowerSources have only one direct input. Some have two, like OrGate, but for now I'm going to see what kind of performance hit I get.

Now, if only I had a performance testing framework in Scala. Does anyone know of one?