I have a test automation suite setup using Selenium and RemoteWebDriver that runs against IE7/8/9/10 and FF10/20/24. The suite takes an average of an hour to complete on each browser except IE9 which takes just over 7 hours.

What could cause this performance hit against IE9 specifically?

1 Answer 1


If you're using xpath selectors that might be the culprit and you could try converting to CSS selectors instead. I understand that xpath engines are different between browsers, while CSS is native which makes it more efficient. Here's a link of a Sauce Labs blog post with more details on CSS vs xpath:


Check out the table in the blog post, there's a big difference in performance speed between CSS and xpath in IE.

  • "XPath engines are different between browsers, while CSS is native". Doesn't that mean that CSS engines are different between browsers as well?
    – dzieciou
    Commented Oct 3, 2013 at 4:36
  • You're right, to clarify what I mean by "native" is that I understand that each browser has their own CSS engine built in. While for xpath IE does not have a built in xpath engine and instead uses a javascript implementation.
    – Francis
    Commented Oct 3, 2013 at 5:22

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