5070 devices update much slower than 5470 All In One

What build are you updating from and to?

The 5070's, wired or wireless?

If they are wired, can you try wireless? 

If they are wired, what is speed and duplex on switch?  What happens if you try hard coding it to 100Full instead of auto?

What CPUs have the 5070 and the 5470? We noticed that our 5070/5470 (Laptops) with the Intel J4105 take considerable more time than the 5070 with the Intel J5005 to update, despite the CPU beeing similar. We have some Optiplex 3000TC with the N6005 CPU and these are really fast.
We reduced the packages to be updated to the minimum required but still the J4105 take around 30-40 minutes to update. So I think the problem is the CPU performance and there is nothing you can do except replace them.

That's odd.  We're seeing the exact opposite as you.  Our 5070 devices with J5005 CPU take much longer to update than the 5470 All-In-One device with the J4105 CPU.

This isn't a network issue.  The 5070 devices download the updates fine both wired or wireless.  It's the time it takes to install the update and reboot the device with is much slow on the 5070s.  I had a device I updated yesterday, it appeared to finish the updating then took an additional 30 minutes before it rebooted itself.  I see this behavior frequently with this model.  It was upgrading 2205 to 2306.

This is really odd. Unfortunately we do not have any 5470 AIO to compare but only some 5470 Laptops with the J4105 CPU and they are slow to update as well.

At first I suspected it was the way how ThinOS 9 was installed the first time as we used both the USB and FTP method to upgrade from 8.6 but the 5470 came already with ThinOS 9 preinstalled and are slow as well. 

Anyway I find the J5005 as well too slow compared with the Optiplex 3000TC with N6005 and Latitude 3420 with i5 CPUs that we have as well.

And this is not a network or server issue as you pointed out. We use WMS in the Cloud and On Prem and the issue persists.