All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=783744

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=1b6705eb2882a17f131404f46335dc980685566f97432b19aec6f26a62a86162


Bot(s) for this bug's original alert(s):

webrtc-win-large-tests

The improvement on October 27 is likely due to the Chrome roll (https://webrtc.googlesource.com/src/+/3ebed36b0184f3ea1beaea17896c53e9d9623dcc) that includes https://chromium-review.googlesource.com/727523 ("VS 2017 15.4 with 10.0.15063.468 SDK").

The second set of improvements (November 11), is less obvious. In fact, the blame range contains the _revert_ of the above indicated update of the VS toolchain, which seems strange.

But, these are improvements, and I'll accept those.