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How will a cascode effect the discharge of the load capacitor? I would expect that the discharge trough the cascade is slower since the cascode has higher output impedance.

schematic

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schematic

simulate this circuit

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It's all about the total resistance. In most cases, that is probably dominated by the resistance of the switch, but ESR (equivalent series resistance) of the cap can also be significant.

The resistance of the switch is the resistance of the two FETs in series in your top diagram. All else being equal, that should be higher than that of the single FET in the bottom diagram. However, all else could easily not be equal. FETs come in a wide range of Rdson values. You also have to look at how the two FETs are driven, meaning do they have sufficient gate voltage in the on case to get to the nice Rdson shown on the front page of the datasheet.

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