How to update many independent materials in parallel?

[DaAwesomeP]

I have many, many entities drawn onscreen and need to update the color of many of them at once. I cannot figure out how to use ResMut<Assets<StandardMaterial>> with par_iter():

fn update_colors(
    mut materials: ResMut<Assets<StandardMaterial>>,
    query: Query<(&MyComponent, &Handle<StandardMaterial>)>,
) {
    query.par_iter().for_each(|(my_component, material )| {
        let material = materials.get_mut(material.clone()).unwrap();
        material.base_color = do_some_math(my_component);
    });
}

Each entity has its own material (set initial with PbrBundle) not used by any other entity. Is there a way to store the material component directly in the entity instead of with a handle?

Doing this not in parallel is not feasible (framerate drops to 1/4 what it was).