[akersten]

> ignores the first 5 results (to avoid caching effects).

This would be the correct approach if you're interested in the "sterile laboratory" performance of these APIs. But the average webpage is going to not be doing a bunch of throwaway work before it starts selecting elements.

I think it would actually be much more interesting to see the cold start results to see if they're comparable to each other. Hypothetically if e.g. GetElementById is only faster after the result has been cached by this simulation, then I think any conclusions about real world impact here could be misleading.

[chrismorgan]

Unless you are accessing elements by ID ridiculously often, the time taken will be utterly unnoticeable rounding error (far below one millisecond). But if the difference is enough to skew the benchmarks, then it makes perfect sense to remove them. (In practice, on removing the skipping, I see no significant evidence that it actually makes a difference.)