It would be good to measure that for the various tools. Things like balance assertions, balance assignments, valuation, may complicate the picture. hledger and beancount users, at least, do often split files by year to keep things in the "pleasantly fast" range.
> If required, you could always close a balance in one file and start with new accounts in a new file, sharding your journal by year, for example.
When I was using double entry accounting down to individual grocery items in GNUCash, I used to do this just for my own sanity.
If required, you could always close a balance in one file and start with new accounts in a new file, sharding your journal by year, for example.