The Fast Layer and the Slow Layer, and Why They Must Be Separated

Ask why a bank is slow and the answer usually points at engineering. It is almost always the wrong place to look. Daniele Tonella, CTO and Member of the Management Board at ING, reckons coding accounts for roughly a fifth of the time in any large project. The rest goes on risk, compliance, and the surprisingly hard work of agreeing what is actually being built — because the moment requirements have to be specific, divergence appears.

Rhythm helps. Joe Wilson, Chief Evangelist at bunq, describes a cadence of three major releases a year with fixes going out whenever they are ready, and features reaching market in four or five weeks.

The structural answer, according to Cornel Dixon, Head of Growth at Plumery, is decoupling. Most banks blend the layer that needs to move quickly with the layer that must not, so a single change can threaten the whole chain. Separate them and you can staff each properly — one team on operational reliability and risk, another building at pace on the foundation underneath. Cornel argues it is exactly what sits beneath a decade of scaling at the best-known challengers, and that the difference is visible to anyone watching how often their apps change.