Improve program performance avoiding useless readings

I would need to improve the performance of a program; in the wrkactjob
command, looking at the opened files and their readings, I realized that
there are some files that are read many times.

I would like to start to avoid useless readings; since the initial program
calls many other programs, and the same file is therefore opened several
times (in the wrkactjob command I find the same file several times)

I was wondering how to individuate programs in the stack, which do a lot of
reading; there is a log / monitor that allows me to understand for a given
job which, records (relative number of records or key) of given file

have they been read and by which programs?

sorry if I wasn't clear enough

Thanks in advance