He regarded this as an advantage, not only because he resented the work involved in preparing for performance as a distraction from composing itself, but also because he was acutely shy and hated being present when his music was performed.
He viewed this as a benefit, not only due to his resentment of the effort required in preparing for performance as an interruption from composing, but also because he was extremely shy and detested being present when his music was performed.