Can be seen when scrolling past the camera section of the page. Most of the time seems to be spent on C_CLIP. It is much easier to trigger with scrollwheel than arrow keys.

GPU: Intel HD4600
Driver: Mesa 19.2.8
Compositor: gnome-shell (X11)

Lots of clipping indeed, visible in the attached render graph. With the texture cache debugging overlay we can see that40 alpha texture array layers are allocated when scrolling past that section, which is likely what's stalling the renderer thread for so long.

That massive alpha 8 texture array originates from a tiled blob mask producing 340 tiles.

Yeah we have:
SVG Image drawing 5512x4600 https://www.apple.com/v/ipad-pro/y/images/overview/camera/cameras_lidar_mask__dl06yo3axpkm_large.svg
SVG Image drawing 2756x2300 https://www.apple.com/v/ipad-pro/y/images/overview/camera/cameras_lidar_mask__dl06yo3axpkm_large.svg
SVG Image drawing 2784x2324 https://www.apple.com/v/ipad-pro/y/images/overview/camera/cameras_lidar_mask__dl06yo3axpkm_large.svg
SVG Image drawing 11024x9200 https://www.apple.com/v/ipad-pro/y/images/overview/camera/cameras_lidar_mask__dl06yo3axpkm_large.svg