I was working at PacBell in San Diego in 1985 when an opportunity appeared. A 53,000 line file of name/value pairs was shipped in from Bellcore. It needed to be processed to remove and modify some of the fields. The COBOL staff in Hayward wrote code to perform the task. It ran 16 1/2 hours. I was asked to write a C program to accomplish the requested changed. My code ran in the UNIX common bank on the same physical machine that ran the COBOL. The exact input file used for the COBOL run was provided to me. My C code did the job in 20 minutes. That was the genesis of a software development career that ended in June 2025 at Leidos.
In the current time, I would write the code in PERL or Python and anticipate a similar run time as the C code. The task was totally unsuitable for a COBOL solution.
I thought Python was relatively slow.
-PJ