slow sorting in firefox (2024)

Oh, one more pertinent piece of information...

I tried with and without sort classes applied. No apparent change in speed based on this.

Hi wcmanes,

wow - 2-3 seconds to sort on only 200 rows really is slow. I've just tried this in Firefox 3.5 using about 250 records and it appears to work okay with my data set, and basic initialisation. Are you using a complex sorting function or anything like that, or is it as simple as $({selector}).dataTable(); ?

Are you able to provide a link to the page which is running slow? The _fnSort function will construct a dynamic function to run (unless you are using AIR - which you aren't...) which is why it's harder to debug further down into the sorting. If you wanted to you could force it to use AIR style sorting by doing window.runtime = true, so your profiler will then pick up the sort functions.

Regards,
Allan

It's actually just over 100 rows and I'm using standard initialization and sort. Have run firebug profiler and it shows a total time of about 100ms, which doesn't make sense to me (some data below). As I said, I only see the slow response in FF.

Tried setting window.runtime and I do not see any change. I will send you a PM with a link to the app.

Profile (107.621ms, 16007 calls)
_fnDraw129.06%31.271msjquery.d...Tables.js (line 2503)
remove()95013.85%14.906msjquery-1.3.2.js (line 720)
add()2377.41%7.977msjquery-1.3.2.js (line 713)
has()13055.43%5.839msjquery-1.3.2.js (line 730)
filter()2194.45%4.786msjquery-1.3.2.js (line 1580)
Sizzle()2193.3%3.548msjquery-1.3.2.js (line 1426)
find()2183.07%3.305msjquery-1.3.2.js (line 1549)
inArray()11872.93%3.148msjquery-1.3.2.js (line 1087)
removeClass()9502.87%3.088msjquery-1.3.2.js (line 1230)
grep()9502.39%2.571msjquery-1.3.2.js (line 1135)
(?)()10682.11%2.269msjquery-1.3.2.js (line 723)
each()4622.09%2.252msjquery-1.3.2.js (line 672)
isXML()8761.87%2.012msjquery-1.3.2.js (line 2339)
add()2231.54%1.654msjquery-1.3.2.js (line 712)
_fnDataToSearch8321.41%1.514msjquery.d...Tables.js (line 3760)
POS()8341.29%1.383msjquery-1.3.2.js (line 2043)
_fnBuildSearchArray11.19%1.279msjquery.d...Tables.js (line 3731)
unique()21.11%1.192msjquery-1.3.2.js (line 1114)
data()9381.07%1.147msjquery-1.3.2.js (line 1275)

Thanks for your great work.
Bill

Did some more debugging. The major issue is related to this code in _fnDraw in the loop through the displayed rows:

/* Remove any old stripping classes and then add the new one */
if ( iStrips !== 0 )
{
$(nRow).removeClass( oSettings.asStripClasses.join(' ') );
$(nRow).addClass( oSettings.asStripClasses[ iRowCount % iStrips ] );
}

Takes about 900ms for the _fnDraw function with 100 rows displayed.

I changed this code to:

(before loop)
var ia = 0;
var ir = 1;

(in loop)
/* Remove any old stripping classes and then add the new one */
if ( iStrips !== 0 )
{
if ( !$(nRow).hasClass( oSettings.asStripClasses[ia]) ) {
$(nRow).removeClass( oSettings.asStripClasses[ir] ).addClass( oSettings.asStripClasses[ia] );
}
ir = ia;
ia = 1 - ia;
}

This modification reduces the time for _fnDraw to between 100ms and 500ms (depending on how many rows need to have their class updated). This is not as "general purpose" as the original code because it assumes there are always 2 classes (even and odd), which as far as I can tell is always true. It does make a noticeable improvement in the sort response time (from 2-3 sec to 1-2 sec). I think this is acceptable, but it may be able to be improved further.

Bill

Hi Bill,

I like it! Nice one - thanks for following up on this. It's given me a few ideas for how to speed the draw up as well, and I'll give them a go, and post back with the results. Certainly your work here is of huge benefit to the project as a whole given how "core" this function is :-) Thanks.

Regards,
Allan

Hi Bill,

A quick update on this - What I've done is basically the same as you've got above, but removed the need for the $().hasClass method call by storing which class is being used for a row in the aoData array. This removes the need for one more DOM interaction, and also one more jQuery call - which should hopefully speed things up just a little bit more :-)

For a few few quick measurements (Firefox 3.5/Mac with 227 records) I'm getting:

Old method: 205mS
New method: 175mS

So a substantial decrease. I'll looks to see if there are further ways to speed things up a bit - I'm sure there probably are :-)

Regards and thanks again,
Allan

Thanks Allan. I would be glad to try out your updates if there is a way I can get your latest code.

Bill

Hi Bill,

I've just sent over a copy of the latest development DataTables file. It's got the change in there, so hopefully you'll be able to see a little improvement (although probably not much more than your own method).

Regards,
Allan