I used REXX on VM/XA (IBM 3090) for a few years, then switched to perl4 when the mainframe got replaced by UNIX and Linux machines in '93.
I switched to perl5 in '95, which meant going through thousands of lines of code, to recode the few perl4 to 5 incompatibilities (well worth it, though) ...

So, a regular perl user since early '90s, now running Linux only, but earlier also on various Unices: AIX, Digital UNIX, HP-UX, IRIX, Solaris and Ultrix.

I use perl for just about everything - anything that doesn't fit in a simple shell function or alias, and have 20-25 years old code still in active use (if it ain't broken, don't fix it :-)

If it can't be written in perl (for performance reasons only ;-), use C, or better still, use a perl XS module or Inline C.