Some technical information about the changes we did for Dart 1.3, to improve server-side performance:
* The HTTP stack, which is written in Dart, was reworked to take advantage of the Dart VM's generational garbage collector. For example, short-lived objects are very cheap to collect, so we now allocate new buffers frequently, instead of reusing buffers.
* On Linux and Mac, we reduced the number of required system calls for asynchronous I/O, which significantly reduced I/O latency. This was accomplished by moving from a combined pull and push based I/O event model, to an entirely push based solution where the OS is responsible for emitting all I/O events.
* We profiled profiled some server-side applications and identified missing optimization opportunities in the Dart VM's optimizing compiler. The VM team also tuned the compiler (for example, inlining strategies and closure calls) for more efficient asynchronous Dart code.
* Again, by profiling some samples, we identified some elements in dart:core and dart:async, that was sub-optimal. (e.g Uri-parsing and toLowerCase).