Maybe you can point out where I was rude. In my reply to @Paryush I was considering the questions raised below and replied that: “…that maybe your business can not be considered small when managing so many items?..” in view that Manager is developed for small business and 68,000 items seem a lot.
Manager slows down significantly be it with large numbers of transactions (receipts and payments) or invoices or GL transaction reports because the SQLite database will try to load all of them into ready access memory (RAM) which also was at the basis of creating pages in Tabs and History. Similar to large amounts of transactions to use as POS as advised Question about database size - #4 by lubos it may be better to use a special-purpose inventory system.