[GTK] WebGL: slow framerate, sluggish panning on the F4 demo 3D map of Paris with lots of trees

• Component: WebKitGTK
• Status: NEW ---

[Jeff Fortin]

Here's an interesting benchmark where Epiphany TP (Skia, WebKitGTK 2.45.90, GTK 4.15.6) + 46.3, and WebKitGTK6's MiniBrowser are all much slower than Chromium:

1. Open https://demo.f4map.com/#lat=48.8525728&lon=2.3478009&zoom=16&camera.theta=43.854&camera.phi=24.064
2. Wait 20 seconds for all the buildings _and all the trees_ to load
3. Click and drag to pan around (don't zoom in, stay zoomed out at the wide view from that URL)

Result: it's sluggish, feels like 10-20 fps. Comparatively, Chromium manages to drag it butter-smooth, at what feels like 40-60 fps.

Demonstration video (Epiphany TP vs Chromium): https://youtu.be/HB0l8BoacEg

This was tested on Fedora 40's Wayland GNOME Session with:

* My desktop with open source AMD Radeon R9 270 Mesa 24.1.6 drivers, kernel 6.10.4, a Xeon CPU, and 24 GB of RAM.
* My laptop with Intel Kabylake graphics, i5 CPU and 24 GB of RAM

[Jeff Fortin]

Created attachment 472318 [details]
Screenshot of a Sysprof capture of Epiphany 46.3 - flame graph

As it's tricky to get good debug symbols / sysprof captures out of the flatpaked TP version, and but the sysprof flame graphs had very similar shapes, I presume this screenshot from the capture of Epiphany 46.3 "with debug symbols" would probably still be useful.

[Jeff Fortin]

Created attachment 472319 [details]
Screenshot of a Sysprof capture of Epiphany 46.3 - marks

Notice the sharp drop of compositing activity in the last five seconds on the right, which is the period during which I have been drag-panning the map with my mouse.