The scrollview do not scroll to bottom if there are two many messages

I was running a batch test, and a large number of log messages was generated. Afeter a period of testing, I found that sometimes the  scrollview was not scrolling to the bottom,  sometime it can scroll to bottom，but along with the jumping of the scroll bar(The scroll bar appears at the top and immediately jump to bottom，seams the screen flickered, the scroll was not that smooth).