The flutter_driver web implementation currently relies on sync sockets: https://github.com/flutter/flutter/blob/master/packages/flutter_driver/lib/src/driver/web_driver.dart#L12

We probably shouldn't be using these, since it can hang the tool or test script to block on a socket connection. It seems like the async versions of web_driver incur additional overhead on closing, but that could be investigated as a bug on its own.

• @angjieli did you ever discover the reason for the 15 second delay?