[whatwg] HTML5 (including next generation additions still in development) - Mozilla Firefox (Not Responding)

Boris Zbarsky bzbarsky at MIT.EDU
Wed Aug 11 18:29:13 PDT 2010

On 8/11/10 9:17 PM, Garrett Smith wrote:
> On 8/11/10, Boris Zbarsky<bzbarsky at mit.edu>  wrote:
>> On 8/11/10 11:48 AM, Boris Zbarsky wrote:
>>> javascript:var start = new Date(); function f(n) { for (var k =
>>> n.firstChild; k; k = n.nextSibling) f(k); } f(document); alert(new
>>> Date() - start)
>> Er, that had a typo.  The correct script is:
>> javascript:var start = new Date(); function f(n) { for (var k =
>> n.firstChild; k; k = k.nextSibling) f(k); } f(document); alert(new
>> Date() - start);
> My result is 1012

In what browser?  Firefox 3.6?  (And presumably on reasonably slow 
hardware, if so.)

If so, really do try 4.0 beta.  It's a good bit faster.

> It's also highly contrived example. When you start doing any DOM
> manipluation, particularly appending or removing nodes, you're going
> to notice a lot larger times.

Well, sure, but you also won't be walking the entire DOM in JS like 
this.  The HTML5 spec scripts sure don't, last I checked.

>> Now the numbers are slightly larger; on the order of 230ms to 350ms.
>> Barely above human lag-perception.  This is on a several-years-old
>> laptop as hardware.
> How do figure that's barely above human lag perception?

The commonly accepted figure for when things start to feel laggy in UI 
terms is 200ms.  If someone clicks and nothing happens for more than 
200ms then they perceive the response as slow.  Otherwise they generally 
perceive it as "pretty much instant".


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