On Tue, Oct 29, 2019 at 04:47 AM, Avgerinos wrote:

I wonder whether this is an indicator that the problem relates to the way Windows are handling W32 apps and their execution-time allowance.

There is no such thing like a "W32 app execution-time allowance". You have such things on mainframe or in the cloud, then however it does not matter if a process is 64-Bit or 32.
You should monitor the performance of the system and if Magic gets slow check if there's something "going up" (like memory, cpu, I/O , ...).
My guess is that Magic , after a while, gets mainly busy with context switches. Thats a wild guess ^^
https://devblogs.microsoft.com/pix/pix-cpu-tools-finding-and-analyzing-context-switches/

Next to this you can install tools to roll your logfiles when they reached a specific size. This will work with Magic because these files are not constantly open.
"Logging" may have a bad impact on application performance btw. too  

I would not monitor Magic with Magic by generating log files. Sucks anyways as you already found out.
Integrate with ELK stack f.i. and log to there (from inside Magic). Next to that you can collect any other information 
With beats f.i. https://logz.io/blog/beats-tutorial/

...

There's a lot to write about "application and system performance monitoring, ..." 

Best regards,

Andreas