Insanely slow search in text viewer

Anybody else having this?

If I view a large text file in the standard Text Viewer and try to search for text inside it, it's very slow. As an example of how slow it is:
I have a 2.88MB text file. I search for some text that I know is not contained in the file. One core of my CPU goes up to 100% and the fan starts blazing away. I wait. And wait some more. And wait a bit more. Still waiting. And then, finally, after 3 minutes 45 seconds, it says that the string wasn't found. This is on a 2GHz laptop, but it does the same sort of thing on two other computers.

This is all on XP in Opus v9.1, but it was the same in v8 as well.

It does seem very slow with large files. I'll take a look.