The only way to archive them would be to merge all the old codes into one "archive" customer code. Doing this would effectively run a "find and replace" in your whole database. For example, if you wanted to convert customers 1001, 1002, and 1003 to new code 9999, it would find these customer codes anywhere in your database and change them to 9999. This includes on quotations, orders, deliveries, invoices, activities etc. so you would need to keep a copy of your system before you did this, so you can still access the historical data.
One question I have is, what is being slowed down by having all these customers? If they are closed they will not appear in reports unless you specifically choose to include closed customers. Nor do they appear in the Paste Customer window. How are users searching for customers?
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