Identifying problems in the GPU graph

Sometimes a scene results in a layer tree that is easy to construct,
but expensive to render on the raster thread. When this happens,
the UI graph has no red, but the GPU graph shows red.
In this case, you’ll need to figure out what your code is doing
that is causing rendering code to be slow. Specific kinds of workloads
are more difficult for the GPU. They might involve unnecessary calls
to saveLayer, intersecting opacities with multiple objects,
and clips or shadows in specific situations.

If you suspect that the source of the slowness is during an animation,
click the Slow Animations button in the Flutter inspector
to slow animations down by 5x.
If you want more control on the speed, you can also do this
programmatically.