Performance for Timer vs DispatcherTimer

Question

I don't have a specific scenario in mind, but this question just crossed my mind while I was thinking of scenarios where I may want to use a Timer over a DispatcherTimer.

In the scenario where I have to perform come computationally intensive task whenever a timer event fires, and then make minor modifications to UI, would it be better in terms of performance to:

1. use a regular Timer and then use the application's Dispatcher to change the UI
2. use a DispatcherTimer (and possibly do my computationally intensive work in some async background worker if necessary).

My guess is that keeping the UI thread unblocked for as long as possible will enhance the user experience. If this is advisable, Are there any catches that I should be aware of in such a scenario?

EDIT:

I get the feeling my question was not clear enough, so I'm going to try and add a concrete, albeit made-up example.

Let's say I have to read a large file every 2 minutes, and when I'm done, I have to add an item to a ListBox. Let's say reading/processing the file takes 10-15 seconds, during which I do no UI work. What would be the best approach for something like this?

Answer 1

Main point:

to perform come computationally intensive task

This would indicate not using the DispatcherTimer. It mainly exists to perform small tasks on the main thread and avoid creating another thread.

If you use a DispatcherTimer to start a Backgroundworker you're circumventing its main purpose.

So just use a regular Timer here.

Answer 2

After some more research and analysis, I've come to the conclusion that a regular timer works best in my made-up example. So far, I haven't had to look out for anything specific that would cause potential problems in my code. Having said that, good coding practices never hurt!