Parameter passing among pages - app very slow - parameter-passing

Question

In my MAUI app I have a first page, let's call it Landing, showing a list of accounting objects. Among them, ExpenseReports.
Each ExpenseReport contains 1...N Expense objects.
Each Expense contains 1..N Receipts.
Each Receipt has three main fields in the database: ID, Image (blob) and Thumbnail Image (blob)
I start by selecting an ExpenseReport on the Landing page.
When navigating to the ExpenseReportEdit page, I send a few params, among them the ExpenseReport object just selected, and a deep copy of it, ExpenseReportOriginal, which will not be altered at all, serving only for field comparison (you will see why below).
On the ExpenseReportEdit page I see the list of the 1...N expenses.
I select one Expense for editing.
Since I will leave this page, I will pass the following params to the ExpenseEdit page:
ExpenseReport, ExpenseReportOriginal, Expense, and ExpenseOriginal.
The ExpenseEdit page gets these four objects and shows the details of this particular expense.
On this page I can take pictures of my receipts. I have noticed that my
[RelayCommand]
private async Task ScanReceipt()
method navigates away from my ExpenseEdit page because I've noticed that, if I set a breakpoint on the OnAppearing method, it gets hit after taking the photo.
So. When taking a photo, I populate a Receipt object. Then I say
Expense.Receipts.Add(receipt);
Expense.Receipts is a list of Receipt objects.
Let's say I have taken 6 photos. The Expense.Receipts list will now contain 6 big (about 7MB each) objects of type Receipt.
After each image taken the code goes again thru the OnAppearing() of the ExpenseEdit page and I can see that the app is already very slow.
I still do not save the Expense object at this point, the intention is to do whatever more edits are necessary and navigate back to the ExpenseReportEdit page (of course, passing the whole Expense object back to it, with all the receipts, and a flag saying "This expense is dirty"). Then after probably some more edits on the ExpenseReportEdit page, the user can finally click on the SaveExpenseReport button, at which point the whole tree will be saved to the SQLite DB.
The "Original" objects are used like so: after each edit on a page, let's say I change field "ExpenseDescription" on some expense, the code in the xaml.cs TextChanged() event will compare the Expense and the ExpenseOriginal objects and if they are in any way different (amy field of these objects), a "changesWereMade" flag is set, thus enabling the "Save" button and also the question "You have made changes on this object etc etc" on the "Back" button if the object was not saved.
If the user clicks on Save on the ExpenseEdit page, I REPLACE the incoming Expense objcet by the just-changed Expense in the Expenses collection of the incoming ExpenseReport I have received, and pass that back to the ExpenseReportEdit page.
If on the ExpenseEdit page the user clicks on Back without saving, I will just send the original ExpenseReport back to the ExpenseReportEdit page.
So let me try to explain a bit better: The code goes like this:
On the ExpenseReportEdit page I can change the ExpenseReport directly.
If I want to change an "Expense" leaf, I click on it, navigate to the ExpenseEdite page. Here I can change the details of the expense. I can also click on Add Receipt to add some image to the Expense object
Any changes in this Expense will be returned to the ExpenseReportEdit page for saving the whole tree (unless the user cancels the changes on this ExpenseEdit page, case in which I replace the Expense with the ExpenseOriginal object and then again navigate back to the ExpenseReportEdit page).
This works. But my problem is now with the heavy load I have to carry along - I have to carry my ExpenseReport with all the Expenses with all the Receipts objects thru memory,
because I do NOT save the images to the DB on the ExpenseEdit page and then populate the list of receipts only with the IDs of those images, I actually carry the whole huge bytearrays with me....
I would love to have this in the Expense model
public List<int> ReceiptIDs { get; set; }
instead of
public List<Receipt> Receipts { get; set; }
With a good smartphone with a powerful camera the Receipts are quite big, and the app is very slow.
So now I see a few solutions - none seems to be okay, however.
a) I save the receipt to the database as a Tentative image, carry only the IDs in the Expense object instead of the ByteArray, and then, once back in the ExpenseReportEdit page, if the user decides NOT to save the ExpenseReport, go to the Db and delete those records. But this is quite ugly, you'll agree.
b) I save the receipt to some static class (image of the tree ExpenseReport -> Expenses -> Receipts) and when saving in the ExpenseReportEdit page, taking the whole object from there instead of carrying it among pages like I am doing now.
None of these "solutions" seems okay to me. So, short of asking my manager for a change of the app so that the user saves the Expense directly on the ExpenseEdit page and does not save the whole tree all at once (you'll agree that this is less than elegant !), what would by my best option ?
I am sure that my object circulation is less than optimal, so then.... where have I gone wrong ?
I really hope I have explained my situation as well as I could, and that I have made myself understood. I'm quite tired right now and I am not sure whether this is the case.
Thank you for reading !