OMG text processing performance 6.7 - 9.5

[Ben Rubinstein]

I'm looking for a hints about where the speed has gone in the current (Unicode 
era) LiveCode text processing. I've been vaguely aware that text processing 
performance suffered in the transition, but haven't needed to focus on it before.

The context is that I'm finally forced to replace an app that's been 
processing data for a client for well over a decade. To date the standalone 
has been built on LC 6.7.11; but now we need to put it on a new platform with 
64-bit database drivers. The performance has gone through the floor, through 
the floors below, through the foundations, and is on its way to the centre of 
the earth.

The first stage of the app - which retrieves a load of data from various 
databases and online sources, does minimal processing on it, and dumps it to 
cache files - is approx 2x slower. The main core of the app, which loads this 
data in and does a vast amount of processing on it to generate various output 
data and reports, has gone from 12 minutes to over *six hours*.

(The server itself is different, and running Windows Server 2016 rather than 
Windows Server 2008, rather than but they're both VMs, quite likely on the 
same underlying hardware, and if anything I'd expect the new server to be more 
performant. Of course I assume that a new version of the OS will always be 
slower.... )

The coding is gnarly - the oldest parts are probably at least 15 years old - 
and I've no doubt it could be made more efficient; but we don't have time or 
budget to rewrite it all. So, are there known gotchas, functions which have 
taken a much greater hit than others, that I could concentrate on to get the 
most ROI in speeding this up?