All graphs for this bug:
  https://chromeperf.appspot.com/group_report?bug_id=842723

(For debugging:) Original alerts at time of bug-filing:
  https://chromeperf.appspot.com/group_report?sid=7db3bfe825d25adf225d022c4b8107d21d8075d3be3447e526324f68fa9994f1


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

win-high-dpi

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/15db6d10240000

😿 Pinpoint job stopped with an error.
https://pinpoint-dot-chromeperf.appspot.com/job/15db6d10240000

__init__() got an unexpected keyword argument 'scope'

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/12f10a05a40000

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/16bc12cea40000

📍 Pinpoint job started.
https://pinpoint-dot-chromeperf.appspot.com/job/12d7b616a40000

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/12d7b616a40000

Make --site-per-process the default on ToT via fieldtrial_testing_config by lukasza@chromium.org
https://chromium.googlesource.com/chromium/src/+/fb1ccf02ee8ca79e1404abfd3a3a7d540b7d2dbd
355.5 → 774.5 (+419.1)

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

📍 Found a significant difference after 1 commit.
https://pinpoint-dot-chromeperf.appspot.com/job/12f10a05a40000

Make --site-per-process the default on ToT via fieldtrial_testing_config by lukasza@chromium.org
https://chromium.googlesource.com/chromium/src/+/fb1ccf02ee8ca79e1404abfd3a3a7d540b7d2dbd
342.5 → 761.9 (+419.4)

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

📍 Found significant differences after each of 3 commits.
https://pinpoint-dot-chromeperf.appspot.com/job/16bc12cea40000

Disable test doubletap-to-jump-forwards-too-short on Win7 by takumif@chromium.org
https://chromium.googlesource.com/chromium/src/+/9e405e24c682904c03fcf620c388fb004b60ec0b
0.4392 → 0.4174 (-0.02181)

Adding fieldtrial config for the IncompatibleApplicationsWarning feature by pmonette@chromium.org
https://chromium.googlesource.com/chromium/src/+/7a86e22e588d7941bde54bdb4a8c58c23e502836
0.4174 → 0.6663 (+0.249)

Make --site-per-process the default on ToT via fieldtrial_testing_config by lukasza@chromium.org
https://chromium.googlesource.com/chromium/src/+/fb1ccf02ee8ca79e1404abfd3a3a7d540b7d2dbd
0.6598 → 0.7313 (+0.07145)

Understanding performance regressions:
  http://g.co/ChromePerformanceRegressions

friendly ping from today's perf sheriff
any update?

Ooops.  This felt through the cracks... :-/

That said, I am not sure if there are any actions we can take:

1. The (limited) UMA metrics don't show a regression in the aggregate results.  See http://go/site-isolation-performance#heading=h.u3cs4xppn2j2

2. It is quite possible that site-per-process is causing increased CPU usage in some specific scenarios (especially ones that require quite a bit of communication/coordination between OOPIFs and the browser process).  We've tried to understand some specific benchmarks/scenarios in  issue 835861 , but that didn't go very far.

Please let me know if there are some follow-ups steps that I could do, or that sheriffs could help with.

Ping! This bug has been flagged as stale by Chrome Speed Metrics bug triage, and it has an owner. Any update on this issue?

Resolving as WontFix per comments in #c13 (and lack of any advice for follow-up steps [asked for also in #c13]).