Flutter Performance Optimization: Fix Jank and Dropped Frames A Flutter application can feel slow even when individual operations look harmless. A large widget rebuild, expensive JSON parsing, excessive layout work, image decoding, or complex rendering can push a frame beyond its deadline. For a 60 Hz display, Flutter has roughly 16 ms per frame . Higher-refresh-rate displays require an even shorter frame budget. Flutter's Performance View is designed to help identify slow UI and raster ...