List updates very slowly and blocks UI

I am building an app using SwiftUI that should display work orders I get from a web service. I have successfully got them from a web service using the following function:

func getAllWorkOrders(completion: @escaping ([WorkOrder]) -> ()) {
        guard let url = URL(string: "http://somedomain/api/workOrders")
            else {
                fatalError("URL is not correct")
        }
        
        let conn = URLSession(configuration: URLSessionConfiguration.ephemeral, delegate: self, delegateQueue: nil)
        conn.dataTask(with: url) { data, _, _ in
            let decoder = JSONDecoder()
            decoder.dateDecodingStrategy = .formatted(DateFormatter.iso8601Full)
            let workOrders = try! decoder.decode([WorkOrder].self, from: data!)
            DispatchQueue.main.async {
                completion(workOrders)
            }
        }.resume()
}

while my WorkOrder struct look like this:

struct WorkOrder: Identifiable, Codable {
    var id: Int
    var ticket: Int?
    var date: Date
    var description: String
    var astue: Bool
    var state: WorkOrderState
    var jobs: [WorkOrderJob]
    var project: Project
}

I have also created a view model which looks like this:

class WorkOrderListViewModel: BindableObject {
    var workOrders = [WorkOrder]() {
        didSet {
            didChange.send()
        }
    }
    var astue = false {
        didSet {
            didChange.send()
        }
    }
    var workOrderState = 0 {
        didSet {
            didChange.send()
        }
    }
    var searchTerm = "" {
        didSet {
            didChange.send()
        }
    }
    var filteredWorkOrders: [WorkOrder] {
        var filtered = workOrders
        if astue {
            filtered = filtered.filter {
                $0.astue == true
            }
        }
        if workOrderState > 0 && workOrderState < 5 {
            filtered = filtered.filter {
                $0.state.id == workOrderState
            }
        }
        if !searchTerm.isEmpty {
            filtered = filtered.filter {
                $0.description.lowercased().contains(searchTerm.lowercased()) || "\($0.ticket ?? 0)".contains(searchTerm.lowercased())
            }
        }
        return filtered
    }
    init() {
        fetchWorkOrders()
    }
    
    func fetchWorkOrders() {
        WebService().getAllWorkOrders {
            self.workOrders = $0
        }
    }
    
    let didChange = PassthroughSubject<Void, Never>()
}

In it, I have a couple of filtering criteria: searchTerm, workOrderState and astue. I have a filtering view bound to those 3 properties. Given that web service is quite primitive and there is no paging or filtering (which means that I can get only all work orders, approximately 2k of them), and I need to filter them by one or many of the criteria, I have a calculated propery filteredWorkOrders in the view model which does the required filtering. My problem arises when I do some filtering. In UI, a have a TextField bound to searchTerm, SegmentedControl bound to workOrderState and Toogle bound to astue. When I apply one of the filtering criteria which drastically changes the number of records (for example when switching from workOrderState=0 to workOrderState=1 where it goes from 2k to just 50), UI gets unresponsive and the filtering lasts 6-7 seconds. However, when changes aren't that dramatic (adding astue=true which makes count of work orders go from 50 to 5) it happens in an instant.

SwiftUI view for the list and a row look like this:

struct WorkOrders : View {
    
    @ObjectBinding var data = WorkOrderListViewModel()
    var body: some View {
        List {
            SearchField(data: data)
            ForEach(self.data.filteredWorkOrders) { workOrder in
                NavigationLink(destination: WorkOrderDetails(workOrder: workOrder)) {
                        WorkOrderRow(workOrder: workOrder)
                    }
            }
        }
            .listStyle(.grouped)
            .navigationBarTitle(Text("Work orders (\(String(format: "%d", data.filteredWorkOrders.count)))"), displayMode: .large)
            .navigationBarItems(trailing: Button(action: refresh) {
                Image(systemName: "arrow.clockwise")
            })
    }
    
    private func refresh() {
        data.fetchWorkOrders()
    }
}

struct WorkOrderRow : View {
    @State var workOrder: WorkOrder
    var body: some View {
        HStack {
            ZStack {
                Circle()
                    .fill(backgroundColor())
                    .frame(width: 20, height: 20, alignment: Alignment(horizontal: .leading, vertical: .center))
                
            }
            VStack(alignment: .leading) {
                HStack {
                    if workOrder.astue {
                        Image(systemName: "bolt.fill")
                    }
                    Text(String(format: "%d", workOrder.ticket ?? 0))
                        .font(.caption)
                    
                    Spacer()
                    Image(systemName: "calendar")
                    Text(workOrder.dateString)
                        .font(.caption)
                }
                
                Text(workOrder.description)
                    .lineLimit(nil)
                }
                .padding([.horizontal])
            }
    }
    
    private func backgroundColor() -> Color {
        switch workOrder.state.id {
        case 1:
            return Color.red
        case 2:
            return Color.yellow
        case 3:
            return Color.green
        case 4:
            return Color.blue
        default:
            return Color.clear
        }
    }
}

What am I missing?