With the exception of the rare case where a bug allows an app to consume CPU/etc while suspended, force-closing an app can lead to a less-than-ideal performance profile as you're requiring all those apps to be reloaded from storage every time.
Good rule of thumb is: if you're not having issues with the app, no need to force close it.
Good rule of thumb is: if you're not having issues with the app, no need to force close it.