They made quite a contrast on stage: the diminutive figure of violinist Alexandra Soumm, resplendent in bright pink evening dress, and the imposing black-clad bulk of conductor Peter Csaba. Both, however, are bundles of energy, which was deployed at full tilt in this performance of the Tchaikovsky violin concerto, closing the violin-laden programme of this year’s Sommets Musicaux de Gstaad.

Soumm is just 23 and has a career that’s sharply on the rise (she plays in London a lot, not least under the auspices of the Radio 3 New Generation Artists scheme). On the scale of clean to dirty violin styles (think Anne-Sophie Mutter at one end, Jascha Heifetz at the other), her timbre is somewhere towards the clean end. The excitement in her playing comes from phrasing: she can accelerate through a run and come to the accent at the end with a real flourish. I don’t know if the tempi last night were faster than usual, but when Soumm is playing, the pace of those awesome runs of notes sounds faster.

She did look a little fidgety and nervous at the beginning, but as the first movement progressed, the Lausanne Chamber Orchestra and soloist seemed to take energy from each other. There’s a movement where the baton is handed back and forth between soloist to orchestra: at each entry, Soumm seemed to ratchet up the energy, and whenever the baton was handed back to the orchestra for a reprise of the powerful main theme, they played it with increased vigour. By the time it came to the first movement cadenza, Soumm was really flying, hairs coming off the bow and flurries of notes singing through Saanen church, the high harmonics crystal clear.

Amongst concerto slow movement melodies, everyone probably has their own favourite. I have two: the Rodrigo Concierto de Aranjuez, and this one. The aching, nostalgic melody melts my heart every time, particularly when it is handed between violin and woodwind. In this performance, it was played every bit as beautifully as I might wish. After the brief end-of-movement cadenza, we were in to Tchaikovsky’s joyous rondo finale - more high speed stuff, more bow hairs broken. The variety in Tchaikovsky's different interludes between repeats of the refrain was splendidly brought to life.

The Tchaikovsky was preceded by Mendelssohn's Scottish Symphony. The degree of actual Scottishness of this work is a matter for debate: leaving aside the odd dance rhythm, the music doesn't owe much to Scottish tradition. What Mendelssohn achieves is a vivid picture of the Scotland of myth: thanes sitting in gilded halls, fearful yet resolute in the face of the auld enemy, dances both courtly and rustic, stately processions under grey and brooding skies.

Peter Csaba is a conductor who believes that music must come straight from the gut - that it's his job on the podium to live and breathe the music and draw it out from his players. For a big man, he conducts with extraordinary physicality, constantly in rapid motion, even in the slower passages. The result was a wonderful feel for the rhythms and accents of Mendelssohn's sound pictures.

In spite of all this energy, I'm not sure that the Scottish Symphony is really suited to the chamber orchestra format. The music often moves from the storytelling style into some enormous tutti, and you just don't get the same impact as you would with a full symphony orchestra. I was left feeling that I hadn't quite received the full effect of what this symphony can deliver.

But by the end of the Tchaikovsky, I had no quarrel with the energy and vivacity that the Lausanne Chamber Orchestra provided. Csaba says that he was once measured as losing 3 kg of weight in the course of a concert, and I can well believe it.