In the original post you wrote:
How long did your test take before you noticed the extreme slowness?
10 seconds? 3 minutes? 20 minutes? or over 1 hour?
Do you regard 1hour as normal? To me, 1hour looks to be an extreme case.
I have ever experienced a lot of strangeness when I ran “hours-running as normal” tests. For example, when I left KS to run for hours, my Windows OS went down to Power Save mode, then every thing including Katalon Studio halted without saving miscellaneous resources; … after resume, KS got crazy.
Long running tests are hard to care, deserve special treatments. I suppose that you should try finding ways to make your tests to run quicker.