It's very true. As a merchant acquirer, everything is BigDecimal, only the auth path needs real performance, and FX occurs at a fixed rate per-day which is easy

It's very true. As a merchant acquirer, everything is BigDecimal, only the auth path needs real performance, and FX occurs at a fixed rate per-day which is easy to reconcile. It's fun reading all the different ways fintech has to adapt their systems for their specific niche.