Apparently highlight.current.word=1 looks through the entire file, even when the file is very large (many megabytes).
This makes the editor unusable with that option, so it should be fixed.
The feature is meant for normal size source code files. If it is too slow in some circumstances then turn it off.
Uh, so what do you do if you have a 100-MB log file you need to view?
If I had a 100 MB file then I would open it in SciTE. If it was too slow then I'd open the user or local options and turn highlight.current.word off.
Uh, no, I kinda _need_ the highlighting in the log file so I can spot duplicates of a word/event...
Since this has been rejected, I am now closing the issue.