Label performance test on iOS. It uses UILabel, WJAsyncLabel, YYLabel.
WJAsyncLabel is a simple asynchronous solution for rendering text. In contrast, YYLabel is more complicated and inconsistent with UILabel.
As seen here, UILabel does consume time on the main thread with drawing and displaying.
As a result, asynchronous solutions have perfect FPS， while UILabel make performance degradation, especially when Chinese character and Emoji exist.
It must also bo noted that, the heights for cell have been calculated and cached in advance, in all different situations.
Whatever.