  We introduce the sudden variant (SNZ) of the Net Zero scheme realizing
controlled-$Z$ (CZ) gates by baseband flux control of transmon frequency. SNZ
CZ gates operate at the speed limit of transverse coupling between
computational and non-computational states by maximizing intermediate leakage.
The key advantage of SNZ is tuneup simplicity, owing to the regular structure
of conditional phase and leakage as a function of two control parameters. We
realize SNZ CZ gates in a multi-transmon processor, achieving $99.93\pm0.24\%$
fidelity and $0.10\pm0.02\%$ leakage. SNZ is compatible with scalable schemes
for quantum error correction and adaptable to generalized conditional-phase
gates useful in intermediate-scale applications.
