An alternative to having to change batch size/timeout settings on export, it might be worth considering adopting a similar approach that Microsoft did with the MIM (Service) MA - i.e. changing the default option to asynchronous instead of synchronous exports.
Under the current default configuration, the MIM MA gets a success returned from the MIM Service once an exported change has been successfully queued (inserted in the REQUEST - either single or batch request objects). A similar approach might be worth considering for IdB such that we can decouple long-running connector export times from the MIM export itself.
I am categorising this request under O365 because that is where I am seeing the most need for this feature right now - however this would be a generic option.
Customer support service by UserEcho