Wunderkindfest. Unless you are a stubborn opinionator, performances can confuse you at times. I was flummoxed last night at the Proms by Gustavo Dudamel and his Gothenburg Symphony Orchestra, in a concert I was expecting to enjoy, though not to the utmost. The Berlioz Symphonie fantastique wore out its welcome many years ago, and only a brilliant performance can redeem it for me. That Dudamel did not deliver. Sparkling as he is in the bright media limelight, the skyrocketing young Venezuelan has to have the goods, too. In this case, his reading was flat, disjointed, and plodding, with a drawn-out Scene aux champs that lasted long enough for Madame Defarge to knit a quilt. The guillotine movement that followed was coarse and blatty, which is how the whole reading went, either in slow mo with exaggerated emphases or sped up recklessly. Dudamel’s inability to sustain tension in soft passages, one of the most blatant failings in a bad conductor, shocked me.