You can display any number of image slideshows, webpages and widgets at the same time.
If the widgets you use require a lot of processing and the hardware is not up to it, you might notice some sluggish animations depending on the type and content of the webpages and widgets.
Important: you can display only one playlist containing videos at any given time. This is a restriction imposed by the Xandabox (Raspberry Pi) hardware, which cannot playback more than one video simultaneously. In most cases, you should not need it.