rendering deformable object(vertex array? vbo?)

what is the best method for rendering deformable object? 1. glBegin() 2. vertex array 3. vertex array buffer object 4. vendor specific vertex array system in my implementation, i need to draw vertices with different world transform (from physics simulation). how can i possibbly gain performance from vbo? i dont really see any possible performance gain when you have to update the world space coordinate every frame. any hint guys? Thanks.