It takes very long to load large device schemas in the Data Explorer view because all attributes are automatically selected and shown in mini graphs. Therefore I request a preselection option of attributes before rendering the individual graphs for selection. This is very much the same as available on the “Data” tab of devices.
We’ve been meaning to redo our Data Explorer for some time now - for several reasons, including the performance issues you’re raising here. I’ll add your +1 and this specific case. Thanks for the feedback.