VM terrible slow and Windows 10 seems to eat up all RAM (12GB), even after fresh boot

Hi there,
my stettings are
MacBook Pro 15" 2018 Editition, 32 GB 2400 MHz DDR4, 2,6 GHz 6-Core Intel Core i7, Radeon Pro 560X 4 GB,
MacOS Sonoma 14.4.1 ( I had read rumors that 14,5 is even slower so I avoid updating it ).
Parallels Pro 19.4.0.
- Hypervisor: Apple
- Adaptive Hypervizor: Enabled
Windows 10 Guest VM ( manually set 4 cores, 12 GB ), not matter using automatic or manual, keeps terrible slow.

I had no performance issues whatsoever before Venture, even with multiple guest VM.
Now I want to use only 1 VM under Window 10, latest version, latest updates.
No update after Ventura showed any significant improvements, now since Sonoma it is nearly unusable to work with.
ActivityMonitor shows kernel_task > 700%, even when there is only very little load under Win10 VM ( approx. 10% ).
If kernel_task is > 700%, then only closing VM and PLS may help, also to cool down CPU fan.
Parallels CPU load is moderate about 40-80%, but kernel_task goes through the roof from time to time and stays there.
When ending the VM, kernel_task gets low again, < 1%, usually the VM is <= 5 %, kernel_task < 1%, Parallels << 1%.
Adding only little load under Windows may cause a kind of thermal runaway.

What I have noticed now:
Before I used
MANUAL: 4 of 6 cores in the VM and 6GB of 32 in the VM, directly >= 6 GB memory load in ActivityMonitor just directly after boot.

I've tried
MANUAL: 4 of 6 cores, 12 GB of 32 GB in the VM, again >= 12 GB memory load in ActivityMonitor just directly after boot.
MANUAL: 4 of 6 cores, 16 GB of 32 GB in the VM, again >= 16 GB memory load in ActivityMonitor just directly after boot.
MANUAL: 4 of 6 cores, 16 GB of 32 GB in the VM, again >= 16 GB memory load in ActivityMonitor just directly after boot ( no load ).
MANUAL: 4 of 6 cores, 24 GB of 32 GB in the VM, again >= 24 GB memory load in ActivityMonitor just directly after boot ( no even logged in ).
==> Memory consumption slowly crawls up to 24 GB.

I've tried
AUTOMATIC: Recommended 6 cores, 8 GB of 32 GB, again >= 8 GB memory load in ActivityMonitor just directly after boot ( no even logged in ).
==> Memory consumption slowly crawls up to 24 GB.

This looks to me, that the Parallels VM always seems to immediately consume the maximum memory it can grasp,
is this the correct, desired behaviour?
No matter if 6, 8, 12, 16, 24 GB, the CPU load might touch the roof when only slighly working inside the VM.

This is really odd and dangerous behaviour,
do you have any recommendations for the best settings, to get best performance without permanent CPU fan blowing?
How can I get back my performant machine before Ventura, what can be the reason ( and I tried already many fixes )?
I'm really out of clue, please help, so that I can get productive again.