I heard a performance of the Mendelssohn Violin Concerto, as performed by violinist Hilary Hahn. What a wonderful performance that was! One major reason for my enjoyment was that Ms. Hahn played certain sections at a slightly slower tempo, and this provided a wonderful level of intimacy to music that has been performed so often.
A key factor that drove this success was the conductor. He let the soloist decide on the tempo, and he provided the expert leadership to have the orchestra support the soloist as she unfolded this wonderful music for us.
Here is Ms. Hahn in this amazing presentation: