Russian Excel problem in encoding

[KanybekMomukeyev]

Hi, thanks for great library!
Have some issues:

(1) I have some problems in text encoding in Russian excel file, what can cause this issue?
(2) Also, it would be best to write some performance test, because in large files it's working slowly.

[KanybekMomukeyev]

Performance test like this one, when there is 1000 objects in array

for (index, orderCSV) in orderCSVs.enumerated() {

                        csv.append([orderCSV.orderId, orderCSV.orderDate, orderCSV.orderType,
                                    orderCSV.customerSupplierName, orderCSV.orderDiscount, orderCSV.orderTotalPrice,
                                    orderCSV.staffName, orderCSV.billingNo, orderCSV.comment])
                        
                                                   }                         
                    }

`

[Nero5023]

Can you give me some examples, so that I can test and fix it?