Very slow JSF Development Mode on tomee 8.x newer than 8.0.6

Hi altogether,

I'm new to this list and hope it's the right place to ask this question. 
If not, and someone know the right place to ask this, please give advise.

I'm developing a big JSF Application for a customer. It's a long running 
project and development and when I started with it, TomEE 8.0.6 was the 
most recent Version of TomEE. The switch to Jakarta is planned for next 
year, so I'm still on the 8.x path for the time being and wasn't able to 
test if this problem still exists in the 9.x branch.

The problem:
On the customers site I'm with the latest TomEE version 8.0.15 (running 
on Java 11) and everything works fine, because it is running in 
production mode. But in my development environment I'm still stuck with 
8.0.6, because there I need the development mode 
(javax.faces.PROJECT_STAGE: Development). I need to be able to see 
changes in facelets without restarting everything everytime, and to get 
more detailed error messages.
My attempts to update my dev TomEE to something newer than 8.0.6 all 
failed, because all (at least all I've tested so far) newer versions are 
so incredibly slow in dev mode, that it's unbearable to use the 
application. Several very looong seconds on every request (even the 
little AJAX requests in a view) is simply not a practical environment. 
After switching to Production mode everything works very fast, and all 
my views have response times of very few ms (even the big ones with max. 
around 400ms). When switching back to Development mode I have response 
times of up to 30s on big views. Not with 8.0.6, there even in 
development mode it's reasonable fast in not getting higher than 1s.

My question:
What causes this enormous performance degradation? I'm hoping, it is 
just a configuration which now has another default value or the like. If 
yes, maybe someone can point me in the right direction of where to find 
this configuration? If it's not a configuration thing: what can I do to 
get around this?

I haven't tested all Versions of TomEE from 8.0.6 to 8.0.15, so I can't 
say at what version exactly this behaviour changes. If it helps or is 
needed, I can make some tests to find the exact version where this 
happens. Versions I've already tested are: 8.0.12, 8.0.13 and 8.0.15. 
All of them are very slow in dev mode. If you need more information, 
I'll try to provide it.

Thanks in advance for any help
cu
Jens