What are "Long Split/Join operations"?

The 64 bit readme coming with 2017r1 contains this sentence:

What is a long operation, please? Does it mean long in terms of running time? Why would that be causing an issue? Like, does it have issues once the operation takes a certain amount of time?!? Or does it mean that it generally takes longer than in 32 bit, and that’s the issue?

English can be so difficult.

I was under the impression it meant there is an issue on longer strings. The longer the string, the more it gets messed up.

There has been several threads about issues with split/join in 64 bit projects. I am sure there are bug reports as well.

https://forum.xojo.com/29075-split-function-in-64bit-is-terribly-slow/0
https://forum.xojo.com/28667-who-s-shipping-64bit/40
https://forum.xojo.com/36825-split-empty-string/0

I remember reading quite a bit during the beta phase as well.