When you utilize the findElement function in Selenium, it does not need to parse the entire page to locate the element. The parsing of the HTML occurs during the initial page load. Additional parsing may occur if there are JavaScript enhancements made to the page (such as using element.innerHTML += ...). Selenium interacts with the Document Object Model (DOM) by utilizing methods like .getElementsByClassName, .querySelector, and others. However, if your browser is on a remote server, or even locally, excessive back-and-forth communication between the Selenium script and the browser can slow down the process significantly. Is there a solution?
Personally, when I have numerous queries to perform on a page, I prefer using the .executeScript method to handle these tasks directly within the browser. This can condense multiple queries into just one. For example:
List<WebElement> elements = (List<WebElement>) ((JavascriptExecutor) driver)
.executeScript(
"var elements = document.getElementsByClassName('foo');" +
"return Array.prototype.filter.call(elements, function (el) {" +
" return el.attributes.whatever.value === 'something';" +
"});");
(Note: The code above has not been tested. Be cautious of any typos!)
In this instance, you would obtain a list of all elements with the class foo that possess an attribute named whatever with a value matching something. (The use of Array.prototype.filter.call is necessary because .getElementsByClassName doesn't strictly return an array and lacks a .filter method.)
If you know that the page content won't change while you analyze it, another option would be to parse it locally. You could retrieve the page's source by executing something similar to:
String html = (String) ((JavascriptExecutor) driver).executeScript(
"return document.documentElement.outerHTML");
This approach will show you the exact page interpretation by the browser. To parse the HTML content, you'll need to employ tools other than Selenium.