[feature] Watch only first X number of lines

[xus2]

Hello, I am watching a page which has very long text, but I only care about the first 100 lines. I haven't found a way to filter for the first X number of lines before starting change detection, is it possible?
Currently I am watching a page with a very long text and when there is a change I get very long and slow to parse email notification. Thank you.

[dgtlmoon]

Could be an easy filter under the filters tab to add