This sounds like a memory issue. 

How many devices are being managed in the zone?

How much ram is assigned to your Windows server? 

Can you provide a screenshot of the diagnostics page from ZCC?

Try adding 4GB to start and see if it gets better.  Note you will need to adjust the heap memory assignment when bumping main system memory, I don't think it does so automatically except during upgrade, but could be wrong.

Also, have you go to page 89 of the zen 23.4 best practices guide for tuning ideas?   https://www.novell.com/documentation/zenworks-23.4/pdfdoc/zen_cm_deployment_bp/zen_cm_deployment_bp.pdf

I would also highly recommend scheduling migration to the appliance

In regards to memory, I do think the current 16GB documented minimum memory is light.  We have added many services over the past few years but have not increased our recommended minimum memory.  I think 20GB is a good minimum (16GB + 4GB as mentioned above.)

It is correct we do not automatically re-adjust memory when memory is added.

To see the current allocation run....

microfocus-zenworks-configure -c DisplayMemoryConfigureAction

To update the current allocation based on recently added memory run...

microfocus-zenworks-configure -c CalibrateMemoryConfigureAction

To see the changes again run....

microfocus-zenworks-configure -c DisplayMemoryConfigureAction

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If you stop Loader...DOes Utilization Drop...

Generally it's ZENServer and ZENLoader as the two primary workhorses.

Stopping Loader will not impact managed devices, as it handles background tasks.

If stopping loader helps, you can look at loader logs and look at things loader such as process inventory files.

If stopping loader does not work, then you need to look at "ZENServer" stuff which revolves around doing assignments, delivering content, etc...