Deelte Webkit Performance Optimization document

This document briefly describes an investigation that was carried out and
the results. This kind of information isn't suitable for the main Apertis
website, it's the kind of information that should be in phabricator.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

content/docs/graphics-webkit-performance-optimization-on-arm.md

-+++
-date = "2014-12-19"
-weight = 100
-
-title = "Graphics: Webkit Performance Optimization on ARM"
-
-aliases = [
-    "/docs/graphics-webkit-performance-optimization-on-arm-f.wkt.7.md",
-    "/old-wiki/Docs/graphics-webkit-performance-optimization-on-arm-f.wkt.7",
-    "/old-wiki/Docs/graphics-webkit-performance-optimization-on-arm"
-]
-+++
-
-# Overview of investigation and results
-
-Two main issues were investigated:
-
-1.  HTML5 canvas demos not getting repaints
-2.  Scrolling performance being poor compared to the image translation
-    reference
-
-## HTML5 canvas demos not getting repaints
-
-This turned out to be caused by higher priority sources starving clutter
-relayout/repaint cycle. It was fixed by lowering the priority of WTF and
-WebCore sources in 3c09afd. On a [specific
-test](https://codepen.io/soulwire/full/Ffvlo), CPU is being used a lot by
-the kernel and the canvas only gets repainted upon input events. This
-needs further investigation. The perf tool has not been helpful, nor has
-GLib debugging, for now. This is not an issue on the desktop.
-
-## Scrolling performance
-
-A while ago, the Clutter actors tiled backing store implementation was
-brought up to date with Clutter's latest developments, which means it
-started using the ClutterContent/ClutterCanvas APIs instead of the
-deprecated ClutterCairoTexture. It turned out that ClutterCanvas kept
-the CoglBuffer created from the Cairo context cached, but recreated the
-CoglTexture for every repaint. By keeping the CoglTexture in cache, we
-match the performance we used to have before that change. A patch has
-been added to our Clutter package, and the fix has also been submitted
-upstream. It has been reviewed and [pushed
-already](https://git.gnome.org/browse/clutter/commit/?h=clutter-1.18).