All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=748522

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=7ad3121ff55b5d18a726e8dff68a75f8425bef41629e812dd0c5f73f2b43daf6


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

chromium-rel-mac-retina
chromium-rel-mac11-pro
chromium-rel-win7-dual

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8973090948305028784

=== BISECT JOB RESULTS ===
Perf regression found with culprit

Suspected Commit
  Author : Ulan Degenbaev
  Commit : 973314f2e1d00831dd525e2214aacf5fb6c86ecb
  Date   : Tue Jul 18 18:03:19 2017
  Subject: Revert "[runtime] Copy descriptors on prototype map transition."

Bisect Details
  Configuration: mac_pro_perf_bisect
  Benchmark    : v8.runtimestats.browsing_desktop
  Metric       : v8-gc-incremental-step_sum/browse_news/browse_news_flipboard
  Change       : 21.16% | 139.329333333 -> 168.807

Revision                           Result                  N
chromium@487661                    139.329 +- 3.1109       6      good
chromium@487662                    136.415 +- 6.19941      6      good
chromium@487662,v8@21a66b11d3      134.504 +- 11.2609      6      good
chromium@487662,v8@973314f2e1      171.725 +- 8.29456      6      bad       <--
chromium@487662,v8@e825c4318e      169.469 +- 13.5181      6      bad
chromium@487663                    169.879 +- 21.786       6      bad
chromium@487664                    171.939 +- 15.6965      6      bad
chromium@487667                    172.784 +- 7.16557      6      bad
chromium@487673                    170.992 +- 10.9581      6      bad
chromium@487684                    173.096 +- 9.82052      6      bad
chromium@487707                    172.599 +- 12.595       6      bad
chromium@487752                    168.807 +- 8.80497      6      bad

To Run This Test
  src/tools/perf/run_benchmark -v --browser=release --output-format=chartjson --upload-results --pageset-repeat=1 --also-run-disabled-tests --story-filter=browse.news.flipboard v8.runtimestats.browsing_desktop

More information on addressing performance regressions:
  http://g.co/ChromePerformanceRegressions

Debug information about this bisect:
  https://chromeperf.appspot.com/buildbucket_job_status/8973090948305028784


For feedback, file a bug with component Speed>Bisection