I'll not have access to the involved systems until next week, so I can't tell about exact .ini file sizes. But trim.bat has done his job since it was run on the file server, I have full permissions, extracted the latest portable build, selected desired options at CCleaner.exe on the server... And then, was noticed the huge delay to start when run from this read-only share, while it keeps using network link (for what? unnecessary).
I've found as conclusive that the root cause of the problem was the way CCleaner works when run from a network share, since the same set of exe and ini's was run with the expected speed when located at a usb flash drive, even before and after running trim.bat.