Cannot highlight in large files

[velidurmuscan]

I am trying to highlight a word in a large file.
The word has about 20 characters.
The file has about 430k lines, and its size is about 100 MB.
When I click highlight, it never highlights the word. I even waited few minutes, but it did not work.
I know that the extension works, because it highlights the same word properly in smaller files.