It is inappropriate to describe FOI / SAR submissions as disruptive and time-consuming and to adopt this approach says a great deal about the attitude being applied.
In reality, a properly functioning organisation with an effective and compliant publication scheme should experience very little disruption since the need for FOIs / SARs would be minimal.
If there are excessive or repeat submissions this should be acknowledged as a 'red flag' for potential systemic failures within the organisation.
A clerk should NEVER regard an FOI / SAR as a 'nuisance' but rather as the trigger for a review of their publication scheme.
To hear that you have a clerk submitting their own FOIs to the council and simultaneously seeking budget uplift and additional hours to respond is wholly irregular!
It very much sounds like your problem is not the frequency of FOIs but rather the action on receipt of them.