Why does dictation reload after not using for 10 minutes?
By default, Enhanced Dictation waits 7 minutes (420 seconds) before quitting its processes. You can override this default by writing a different value to its preference file.

For example, if you want Dictation to wait 60 minutes (3600 seconds), open Terminal and execute the following command.

defaults write com.apple.inputmethod.ironwood DelaySecondsUntilTerminatationOffline -float 3600;killall DictationIM


If you want to return to the default value, you can remove the override using the command:

defaults remove com.apple.inputmethod.ironwood DelaySecondsUntilTerminatationOffline;killall DictationIM