If you set the Feature Layer refreshInterval to less than a minute, your features flicker on the map. I realize they have to refresh, yet could there be a way to refresh the map using AJAX or something along those lines where the data does not flash at every instance of an update? Or, only update the features that have changed and not all the features in that layer? With the GeoEvent Processor and going more towards "Real-Time" data, customers what to see their features moving on the map almost simultaneously or very close to it. If I update the Feature Layer every 1 second, the data is constantly flashing on the map and doesn't look good. This is the same for the Refresh Interval on your Feature Layer in ArcGIS Online, if set to 0.1 minute and also with the JavaScript API.
Here is the code for the JavaScript Web App that I was using:
//geoEvent Feature Layer
geoEventFeatureLayer = new FeatureLayer(geoEventFeatureService, {
mode: FeatureLayer.MODE_ONDEMAND,
outFields: ["*"],
refreshInterval: 0.01667, //in minutes (1 sec)
infoTemplate: infoTemplate
});