So that new profile seems to be showing unstyled content for ~960ms. Most of that time is spent on a 656ms Rasterize operation, which seems to be spending its time in mozilla::layers::ShmemTextureData::Create (in 2 separate calls, I think, each of which take >300ms) So, that's where the perf issue seems to lie. --> Moving to Graphics::Layers.
Bug 1551526 Comment 6 Edit History
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So that new profile seems to be showing unstyled content for ~960ms. Most of that time is spent on a [656ms Rasterize operation](https://perfht.ml/30mMZos), which seems to be spending its time in mozilla::layers::ShmemTextureData::Create (in 2 separate calls, I think, each of which take >300ms). So, that's where the perf issue seems to lie. --> Moving to Graphics::Layers.