All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=727743

Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?keys=agxzfmNocm9tZXBlcmZyFAsSB0Fub21hbHkYgIDghorYvgoM


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

chromium-rel-mac-retina

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8978151886316967552

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8978151876454135152

=== BISECT JOB RESULTS ===
NO Perf regression found

Bisect Details
  Configuration: mac_retina_perf_bisect
  Benchmark    : media.tough_video_cases_tbmv2
  Metric       : video_animation:power_max/video.html?src_garden2_10s.webm

Revision             Result                  N
chromium@472892      44.7184 +- 3.22347      21      good
chromium@475253      45.0725 +- 3.33518      21      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=video.html.src.garden2.10s.webm media.tough_video_cases_tbmv2

Debug Info
  https://chromeperf.appspot.com/buildbucket_job_status/8978151876454135152

Is this bisect wrong?
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5236110877261824


| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Speed>Bisection.  Thank you!

Started bisect job https://chromeperf.appspot.com/buildbucket_job_status/8978136806268099456

=== Auto-CCing suspected CL author pmonette@chromium.org ===

Hi pmonette@chromium.org, the bisect results pointed to your CL, please take a look at the
results.


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

Suspected Commit
  Author : pmonette
  Commit : 7b9e78161bd4fa3e6e057344321e0a82cdceee3f
  Date   : Thu May 18 18:58:01 2017
  Subject: Remove the usage of BrowserThread::FILE in the antivirus metrics files

Bisect Details
  Configuration: mac_retina_perf_bisect
  Benchmark    : media.tough_video_cases_tbmv2
  Metric       : video_animation:power_max/video.html?src_garden2_10s.webm
  Change       : 4.91% | 39.18495324 -> 37.2605858283

Revision             Result                   N
chromium@472892      39.185 +- 1.38665        6      good
chromium@472893      33.0228 +- 2.64271       6      bad       <--
chromium@472894      33.0464 +- 3.19992       6      bad
chromium@472895      33.259 +- 2.25886        6      bad
chromium@472898      33.4732 +- 0.980146      6      bad
chromium@472903      33.0094 +- 2.72889       6      bad
chromium@472911      33.0394 +- 2.69189       6      bad
chromium@472929      32.8653 +- 2.53128       5      bad
chromium@472966      32.1511 +- 2.78345       6      bad
chromium@473040      32.9778 +- 2.43147       6      bad
chromium@473188      31.897 +- 2.02423        6      bad
chromium@473483      33.0163 +- 2.77626       6      bad
chromium@474073      33.073 +- 2.26175        6      bad
chromium@475253      37.2606 +- 0.800091      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=video.html.src.garden2.10s.webm media.tough_video_cases_tbmv2

Debug Info
  https://chromeperf.appspot.com/buildbucket_job_status/8978151886316967552

Is this bisect wrong?
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5033260914049024


| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Speed>Bisection.  Thank you!

=== BISECT JOB RESULTS ===
NO Perf regression found

Bisect Details
  Configuration: mac_retina_perf_bisect
  Benchmark    : media.tough_video_cases_tbmv2
  Metric       : video_animation:power_max/video.html?src_garden2_10s.webm

Revision             Result                  N
chromium@472892      33.1198 +- 4.77785      21      good
chromium@475253      32.7708 +- 4.90235      21      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=video.html.src.garden2.10s.webm media.tough_video_cases_tbmv2

Debug Info
  https://chromeperf.appspot.com/buildbucket_job_status/8978136806268099456

Is this bisect wrong?
  https://chromeperf.appspot.com/bad_bisect?try_job_id=5236110877261824


| O O | Visit http://www.chromium.org/developers/speed-infra/perf-bug-faq
|  X  | for more information addressing perf regression bugs. For feedback,
| / \ | file a bug with component Speed>Bisection.  Thank you!

Closing this bug

Increased CPU time is totally expected from my feature. But the extra work is scheduled on a background thread and should not interfere with foreground work.

In addition, the extra work I am doing is a one time occurrence, that happens shortly after startup. A series of tasks is posted sequentially for each loaded DLL in the process (InspectModule() in module_info_win,h), and each tasks takes less than a second. It may seem long but keep in mind that this runs on a background task. Our metrics shows that the median amount of loaded DLLs for users in the wild is 120.

So unless we see more pref regressions that doesn't involve CPU time, this is working as intended.