Scope::settings() is too slow

[Albert Astals Cid]

Evaluating

settingsEnabled: scopeView.scope && scopeView.scope.settings && scopeView.scope.settings.count > 0 || false

in GenericScopeView.qml takes around 300 ms when running on the phone, which basically feels like an eternity if you're trying to use the phone to scroll, change to another scope, etc

If this needs heavy calculation this should be either pre-calculated and cached or calculated in a separate thread and then signalled with a signal.

[Paweł Stołowski (stolowski)]

From a quick look the problem is most likely caused by Scope::settings() getter, which calls update_child_scopes() every time settings model is accessed by the getter, and this involves IPC with m_scopeProxy->child_scopes() call, which is a blocking call.