If you are splitting on ASCII characters, and your strings are ASCII or UTF8, in older versions of Xojo, one should use SplitB() rather than Split(). One of the great things about UTF8 is that you are guaranteed that there will never be a non-ASCII character that has the same code point.
However, I just tested it, and found this result (Xojo 2023 R4, built app, Intel core i9, macOS Ventura):
36 seconds Split()
36 seconds SplitB()
I was surprised to see no change - I’m pretty sure in earlier versions of Xojo the Split vs. SplitB difference was big. Did Xojo optimize Split() at some point?