I have an application behaving like autorefresh. It checks emails, new videos, jokes, etc.

My client wants these single elements check in different intervals. For example emails every minute, videos every hour, etc. So there should be option for him to write down intervals by himself into textboxes and by checking appropriate checkbox start/stop refreshing.

Application is written in wpf. My question is, whether is better option to add more DispatcherTimers(DT), one for each of elements or stick with only one DT and in tick function make switch?

Also, I assume that DT's tick method runs main thread. Am I right? Is it better to run operations inside tick method on different thread if possible?

By default WPF Application has single thread - Main UI thread and all UI controls/windows are created and associated with it. In this case I do not see any benefits usign multiple Dispatchers and Dispatcher Timers since anyway Dispatcher Timer would delegate all messages to the associated Dispatcher's messages loop what would be a Main UI thread message loop.

But if you've created some controls in separate worker threads like

var thread = new Thread(() =>
         {
              CustomWindow wnd = new CustomWindow();
         };

And would post messages to this window as well - then it makes sense creating a new Dispatcher and associating with a manually created thread, so basically each Dispatcher will be associated with own thread, so relation is 1 to 1.

Regarding atick method - it would be executed on the associated with Dispatcher thread. If you've not created dispatcher associated with a manually created worker thread, so by default WPF Dispatcher associated with the main UI thread,

MSDN:

Reasons for using a DispatcherTimer opposed to a System.Timers.Timer are that the DispatcherTimer runs on the same thread as the Dispatcher and a DispatcherPriority can be set on the DispatcherTimer

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