54L15 Timer Interrupt cost too high. How to reduce interrupt cost?

[Austin (S.F.)]

As title

    Situration:

    1. Timer00

    2. every 4us interrupt occur

    result:

    1. Enter Timer interrupt cost 700ns

    2. Leave Timer interrupt cost 200ns

    3. Totol cost: 1.04us

    How to reduce inrerrupt cost from 1.04us to around 200ns?

   Austin