Ouch! This is from a test published at the IMP3Net forum [Google Translate].
The video after the break looks very bad.
What I think is going on is that the software being used hasn’t been written to taken into account an octa-core CPU. And someone in the IMP3Net forum points out that the app in question might be using the lower-power cores since PDF reading is — ha! ha! — considered undemanding.
The test file is a 151MB PDF. The smaller tablet is using the Rockchip 3066 CPU, the larger tablet is the octa-core Allwinner A80-based Onda V989.
As a contrast, here’s the Xiaomi MiPad handling a very demanding PDF (size of the PDF is unknown, but being filled with images, it must be large — it might also be the same PDF as above):
That even the Xiaomi MiPad — with its blistering K1 CPU — momentarily displays a blank pageholder is distressing.
I think PDF reading software developers have to modify their apps to take advantage of this new generation of CPUs from Nvidia, Rockchip, and Allwinner.
They should have user-selectable options to call upon the more powerful cores to increase reading performance even if that means a bit of a battery hit.
It might seem like a small thing to have to wait a second — or even a fraction thereof — to resolve a PDF page, but those seconds add up when dealing with reading thousands of pages. No one would tolerate such a delay in any other kind of tablet or desktop PC use — and PDF readers shouldn’t have to, either.
(For newcomers, my primary use for a tablet would be to read Google Books PDFs, which can be huge — some approach 1GB. Also, they’re scans of pages, so they really hammer a CPU. See the Google Books PDF category.)
Previously here:
Onda V989 Gets First Review
Demo Video Of Onda V989
Behind The Scenes Peek At Onda V989 Packing
Onda Acknowledges Two Iterations Of V989
First User Reports: Onda V989
Onda “Sells Out” Second Tiny V989 Beta Test Supply
Onda Makes Battery Life Claim For V989
Onda Ships Beta Test V989 Tablets
Onda “Sells Out” Tiny V989 Beta Test Supply
Onda Adds V989 To Their Site
Onda V989 Goes On Beta Test Sale July 14th
Onda’s Benchmark Claims For V989 A80-Based Tablet
Onda Leaks Allwinner A80-Based V989
Onda’s New A80, Windows, And 4G Tablets
Mike Cane’s xBlog 
To be honest. Sometimes even my i7 2.4ghz laptop have some noticeable pauses when scrolling PDFs.
This is can also be caused by slow / low quality storage and not by a slow cpu…
When loading larger PDFs from a slow USB2 stick or external harddrive on my desktop PC (i5-3470 CPU, so more than capable) and then scrolling like the way they do it in the video I get these loading times aswell… (atleast when loading for the first time – after that the PDF is stored in the RAM obviously).
But when loading those PDFs from a fast USB3 stick or even from my Samsung 840 EVO SSD everything is loaded immediately.
So before interpreting too much into it, I would wait till someone does this test with loading from the same high class / very fast microSD card on both tablets.
From reading the thread, both PDFs were being read from internal memory.
What can also affect reading is the app being used. I’ll have to do some research about which PDF reading apps are the fastest, later.