Hi,
It’s because of the amount of text you are printing to the page and probably in combination with the keyword highlighter. I’m looking at the extracted texts, some of those are really really long and it eats up browser memory. It isn’t related to the search process, but the amount of data pushed to the page, it is way too much.
I would suggest turning off the keyword highlighter first, to see if that changes anything. It would explain the lag, as it has to parse through thousands of pages on page load and the browser memory spikes through the roof. If that doesn’t help at all, then it’s a script somewhere in elementor that tries to deal with the data and just fails. Then try to completely remove the extracted text, that should immediately resolve the problem.
The best solution would be to not load the text during page load, but to mitigate it to an asynchronous handler via rest API to load the text when the user clicks on the “view extracted text” icon. Nothing too complicated, only a single rest endpoint and a handler, that should do the trick. Not sure if Elementor has support for loading data asynchronously though, you may have to custom code it.