How to make sales report more "scalable"?

I built an application to keep track of the sales. In my customers view, I want a column with total sales per customer, but as the customer base is growing, the list is loading more and more slowly. This is what I did (simplified):

Controller:

$customers = App\Customer::get();

View:

@foreach ($customers as $customer)
 
@endforeach

Model:

public function totalSales()
{
     $invoiceLines = InvoiceLine::whereHas('invoice', function ($query) {
        $query->where('customer_id', $this->id);
     })->get();

     $sales = $invoiceLines->reduce(function ($carry, $invoiceLine) {
        return $carry + ($invoiceLine->quantity * $invoiceLine->pricePerUnit);
     });

     return $sales ?: 0;
}

What would be the best way to make this view/report more "scalable"?

I have been thinking in creating command that calculates the total sales per customer overnight and put the result in the customer table, but that means that the numbers won't be accurate during the day...

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