@gaosongChina it doesn’t have to be 300ms to 500ms, it could be 10ms if you NEED it to be that frequent. The point is it should be done with a timer rather than in the main loop(). As you expand your sketch if you have much more than Blynk.run() and timer.run() in the loop() it will start to fail.
I hadn’t realised you were using a physical LCD that requires a particular format.