That depends on how you're using the term "circulation." In its strictly technical usage (as far as I know), circulation is just the total issued currency minus any withdrawn currency. That would mean that any banknote that remains legal tender, regardless of intended or actual usage, is in circulation as long as even one specimen remains intact and outside of the control of the issuing bank. Under this definition, I'm fairly certain that the 1988 100,000 peso banknote from the Philippines would be the largest, though it's very unlikely to ever be used in everyday transactions.
If, however, you mean "circulation" in a more colloquial sense (regular transactional use), that's much more difficult to answer. You would not only need the physical dimensions of every banknote that remains legal tender and their production numbers, but also detailed anthropological data on how people in every country/region use those banknotes in everyday life. Many countries might have physically (or denominationally) large banknotes that nobody ever really uses despite their legal status. You could probably make a decent guess for a lot of common currencies, but not for all of them.
The note you are referring to is Brunei P-20 which has been withdrawn or maybe demonitized now.
Here in Thailand last year saw the release of 1000 baht commemorative that was oversized and quite large. People were encouraged to use them for regular transactions. I got copies the day they were issued and have never seen a single one in use since then. Banks don't even have worn copies to give out. Technically they are in circulation but nobody uses them.
