scrolling problems when using the touchpad guesture of MACBOOK

if there are many lines in the left side, and the lines are out of the screen, then if I scroll the left side of the screen in both upward and downward directions with two-fingure-guesture of the built-in touchpad of the APPLE MACBOOK, the macdown software seems jammed, and there is a resilience in the jamming zone.

如果左侧区域有很多行并超出屏幕，使用苹果笔记本自带的触控板手势（双指滚动）时，软件显示就像被卡住了一样，一弹一弹的。