We continued the work from 1.16 of working closely with some of our key users at Google to make sure Dart is even more productive for developers.
We've additionally optimized how our core tools deal with large applications, and have seen significant improvement over the last two releases. Dartium is now much more stable. We have improved the speed of the Dart Analyzer by more than 200% on large codebases. Last, but not least, Dartium startup time on large applications at Google has improved by a factor of 4.
We also made a number of smaller changes to core SDK APIs, please refer to the SDK changelog.