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Comment by chinathrow | Hacker News Reader

Maybe the linked page is not badly coded at all - maybe that is done on purpose. Has anyone debugged why the mentioned page [1] is consuming so much CPU time?

[1]

http://www.xe.com/currencycharts/?from=EUR&to=USD&view=1M

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It wasn't for me. I've let it sit for a couple minutes too. I can get it up to about 20% if I'm sitting there mousing over the chart with 2 years of data but other wise it doesn't seem to do too much.

I've noticed some site's scripts really don't like coming back from a long sleep so maybe it was some edge case like that causing it to eat so much CPU.

When running Chrome, the CPU goes into the 15% to 20% range when running the mouse in circles over the chart on my Windows 7 box at work. When running Pale Moon, I get about 10% to 15%, even after allowing all javascript domains in NoScript. Of course, I'm still running an ad blocker and don't see the top and right-hand column ads which makes me wonder if the author happened to catch an ad that was coded badly.

That's pretty much my setup but with Windows 10 and uBlock and matches what I saw.

Well, I can confirm this happens for me on laptop. When I came to work after writing this post, I checked the page mentioned in the article again on my ubuntu at work (desktop machine) and the metrics were nothing special.

It is indeed the page for me. I profiled the page, even found the function. It seems like the events are fired again and again, multiple times per MILIsecond. Here is the screenshot http://awesomescreenshot.com/0375n2a4c4

And the CPU profile if anyone will analyse it further: https://dl.dropboxusercontent.com/u/47486136/CPU-20160217T17...

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