300 microseconds is a baseline.  We should also consider occasional heavier bindings, such as the omnibox suggestions.  These could be adjusted to compare only a sequence number, rather than all strings and formatting descriptors (for example).

It's pretty tightly distributed around 250us presently, but you're right. I took a trace of an interaction with the omnisuggestions and the bindings can creep up to ~1.1ms.

Interesting they got that high.  I traced on a Pixel 2 and saw them go from 0.194 ms vs 0.257 ms for a full batch of suggestions.  Either way, it's worth consideration.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6

commit 0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6
Author: Ian Vollick <vollick@chromium.org>
Date: Mon Apr 09 15:47:09 2018

[vr] Prune UI tree walks

This CL cuts unnecessary work from our tree walks where we can.

Bug:  828684 , 828688 , 828687 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_vr;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I3706deec5adeae6b4c4d186d45187854e79a840f
Reviewed-on: https://chromium-review.googlesource.com/1000430
Reviewed-by: Christopher Grant <cjgrant@chromium.org>
Commit-Queue: Ian Vollick <vollick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549185}
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/elements/content_element_unittest.cc
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/elements/linear_layout.cc
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/elements/ui_element.cc
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/elements/ui_element.h
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/elements/ui_element_unittest.cc
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/ui_scene.cc
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/ui_scene_creator.cc
[modify] https://crrev.com/0c10c3c2b5261d746fc4455fe0ffe134cdfb38b6/chrome/browser/vr/ui_unittest.cc

As per discussion with vollick@, declaring this complete.