When I attempted import of my investment account, I saw a warning pop up that it was more than 1000 entries and TurboTax might be "slow". Well, I figured I'd live with it.
The import finished and TurboTax was dead. I clicked on the "File" menu and the status bar said "(not responding)". That's beyond "slow", that's "dead".
I looked for how to submit a large number of transactions, and I got
https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/e[product key r...
which says that 100,000 transactions can be submitted PER ACCOUNT. That's an outright lie. I've seen that the number is 1,000, or maybe 1,500. I guess nobody knows for sure. Maybe the limit is based on the phase of the moon, or your accountant's shoe size. You would think that if they programmed it for some maximum that it would know the limit was reached, protect itself, and issue a message.
Also, that page doesn't say how to submit the PAPER records to the IRS, given that TurboTax can't handle them. You can find the address from TurboTax itself when you enter the summary data about the account.
