I can give you a little insight into what is going on behind the scenes and that will at least explain the behavior, but the root cause may be a little more elusive.
First, it’s important to point out that all media browsing operations (regardless of service) happen on the Mosaic Processor in your dCS device. Mosaic Control is simply a front-end to those operations. That means that when you’re browsing your UPnP server all of the actual work is being done by your dCS device, not Mosaic Control.
The browsing lists are sourced from the Mosaic Processor on your dCS device. Artwork is fetched directly from the UPnP server by Mosaic Control.
When a browsing list is requested we use a lazy loading mechanism to fetch a small number of entries (40) and then request the rest of the list items in 40 entry chunks as you scroll through. This mechanism is fast and avoids the waste of resources that would be seen if the entire list was requested at the start.
The delay that you are seeing is a result of Mosaic requesting the second 40 item page from the server. There should not be any delay here so what you are seeing is not normal.
Unfortunately, this is a behavior that I have not encountered and I use similar iPad devices on a daily basis (specifically air 1 / air 2 / mini 2). Given the way that the entire process works and the fact that you aren’t seeing the same issue on Android narrows things down quite a bit.
- Resource issue on the Mosaic Processor – This would impact Android as well, but with a transient issue that could just be a matter of timing.
- Network issue between iPad and UPnP server – This would account for the behavior due to a delay in loading artwork thumbnails. Again the fact that Android isn’t having issues suggests that this has a low probability, but there are cases where different devices will interact with a network in different ways due to differences in hardware and operating system network stacks.
- Resource issue on iPad – There’s a good chance that some other process or activity on the iPad is chewing up resources and this is having a negative impact on Mosaic Control. iOS is very good at isolating apps from each other, but some background tasks can eat up more than their fair share of resources.
Here’s what I recommend you try:
- Power-cycle your dCS device. Although I don’t think that a resource issue on the Mosaic Processor is the root cause this is worth trying.
- Reset your iPad – Close all apps on the iPad (double-tap the home button then swipe up on each app shown). Now hold down the power button and the home button until the iPad reboots and shows the apple logo on the screen. This means holding the controls down through the “swipe to power off” screen until you get the white apple on the black background. This will reset the OS and all running processes.
Out of curiosity, how many albums are in the list that you are trying to view?