>What is the cheapest way to exchange a large amount (7 figures) of euros into Swiss francs?
Interactive Brokers.
Or call your bank and press them hard into giving you a good spread. Not the exchange rate itself - understand that the bank can't control it, and in the price spectrum you're looking at they cannot afford to take the risk of fixing it for you for more than a few moments. You're only going to be able to negotiate the spread they charge you from the market rate. Works with some banks. I've heard from a colleaugue PF gives 5bp spread over the phone. It's not as good as IB, but shockingly good for a swiss bank!
> Would I get a better rate by trading forex with Swissquote?
Nope, their default spread for currency exchange is about 1%. But you can try calling them. The low, single-digit pip spreads they advertise in the big print are for CFD trading only, i.e speculation on the rate, not a vanilla currency conversion.