I have a view on a collection of RecentTrades objects that are populated by a background task fetching using a URLSession.

My view looks like this:

struct StatusView: View {

    @ObservedResults(RecentTrades.self) var recentTrades

    func tradeCountColumn(x: RecentTrades) -> some View {
        Text(String(x.trades.count))
    }

    func isFetchingColumn(recentTrades: RecentTrades) -> some View {
        recentTrades.isFetching ? AnyView(ProgressView()) : AnyView(Text("Loaded"))
    }

    var body: some View {
        Table(recentTrades) {
            TableColumn("Pair", value: \.name)
            TableColumn("Trade count", content: tradeCountColumn)
            TableColumn("Loaded", content: isFetchingColumn)
        }
    }
    
}

My RecentTrades model looks like this:

class RecentTrades: Object, ObjectKeyIdentifiable {
    
    @Persisted(primaryKey: true) var name: String
    @Persisted var last: String
    @Persisted var trades: List<Trade>
    @Persisted var isFetching: Bool
    
}

class Trade: EmbeddedObject {
    
    @Persisted var price: String
    @Persisted var volume: String
    @Persisted(indexed: true) var time: Date
    @Persisted var buySell: BuySell
    @Persisted var marketLimit: MarketLimit
    @Persisted var miscellaneous: String
    
}

Unfortunately, this is super-slow. There are a number of Tasks fetching trades using a URLSession for each pair of coins, but it is only when this view is open that the application grinds to a crawl in terms of responsiveness. I am really interested only in the isFetching property and the count of the trades List on my RecentTrades model.

There are around 50 or so RecentTrades objects in my Realm, and some of those have up to 1,000,000 Trades in the trades property.

Is there a way to improve the efficiency of this view, so that I don't have to fetch the entire collection when any of the properties of the objects inside change? I know I an set up a change listener, but is this going to be any better? Will this still not deliver all of the objects, or does this method fetch lazily so that I can count without having to fetch all of the objects? Why does the ObservedResults not behave like this too?