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Xfconf 4.10 Roadmap
Maybe the deamon can cleanup channels that haven't been used for a while, but that is not really an issue since basically every opened channel is also used by at least one of the core components.
It's not really an option to quit the daemon after a short while since it is commonly connected to user interfaces with the binding, so that might result in slow UI reposiveness.
It may work on a long timeout (after 1 day of serving the planet) it would be hard to notice and still be effective if people keep on their pc on for a long time (including suspending) to keep the number of unused channels and memory usage low.
Watched the xfconfd memory usage and this won't be an improvement. Although the delay is not noticable we're taking about 1mb difference or so, so not worth the possible problem of loosing settings and things like that.