iPad getting hot when using DTG

My iPad 6th gen. is getting hot in the right side (portrait mode) when using the DEVONThink To Go app. I have many .pdf documents synchronized between the main and the mobile apps through the Bonjour service. Always when I am trying to read the documents, the iPad gets hot. This does not happen with no other app. Also, this does not happen when using the Bookends iPadOS app, which seems to be build in a very similar manner to DTG. I am guessing there is some sort of bug that uses the power of the tablet. Now and then I see a rolling wheel in the upper right corner of the .pdf that I am reading. I have stopped the Bonjour service and deactivated the iCloud backup but with no avail. Any help?

Could you please try this with the app “PDF Viewer” from PSPDFKit? They use the same library that we use.

Thanks for the suggestion. I opened some .pdf documents in the app you indicated, and read them as if on DTG, but the iPad does not get hot. Any other suggestions?

Define some PDFs, i.e. number and size of each.

Now I have around 100 .pdf documents. I opened a 5 Mb document, started reading, and the iPad started to warm up. The same happened when I had around 20 documents in DTG. I use other apps for .pdf documents and I open several in tabs but this does not happen.
The sizes vary from 1 Mb to some documents (OCR-ed with the main app) which have around 300-400Mb. Still, opening a big size document in other apps does not warm the iPad.

And the iPad warms up every time you open a PDF in DEVONthink To Go but not in, say, the same document in PDF Viewer? Do you have a system information app that tells you like the CPU usage? Does it go up when DEVONthink To Go runs and shows a PDF? Does it go down when you don’t view a PDF but another document type?

We’ve run some tests here and don’t see any unusual activity when viewing PDFs compared to doing anything else in DEVONthink To Go.

I installed an app (Status Lite) that gives me the live CPU usage. I closed all the other apps. Only Status Lite and DTG are opened.
I did some testing:

  1. When I open the DTG app (no PDF document opened yet), the usage is below 10%.
  2. I open a 20 Mb PDF. Usage below 10%.
  3. If I am scrolling the pages continually, the usage is between 40%–50%. If I stop, the usage falls under 10%.
  4. If I edit the document and highlight with the finger, the usage goes slightly beyond 20%.
  5. If I scroll with Apple Pencil continuously, the usage is around 50%.
  6. If I edit with Apple Pencil (highlight), the usage goes beyond 50%. If I select the text and do not release it (that is, I do not lift the Pencil), the usage does not go below 50%. It seems that it has an issue with the Apple Pencil.

What I also noticed is that, when I view another document, the CPU usage goes up very fast. Sometimes it hangs at over 60% for a second or two. Does not happen always.

I tried the PDF Viewer app. Same steps. Only at step 6 the CPU usage is the same. For steps 1–5, the values are below those shown when using DTG.

It’s perfectly normal that the CPU usage goes up when switching documents. The file has to be loaded, views set up, the document rendered. So all in all this looks normal. The high CPU usage while the pencil is down on the PDF also seems normal as the CPU has to do a lot of processing to detect the pencil and the app to decide what to do. You should see the very same behavior in PDF Viewer.

These may be normal, but do not explain why my iPad warms only with DTG. I don’t have any other option that to use PDF Viewer for editing my documents, even though I was hoping to use DTG. Hopefully in the future this problem will be solved.