Slow performance with custom comparator (AdvancedDataGrid sorting)

Question

I'm using Flex 3.4.
I have an advancedDataGrid. Have 2 columns with numbers as data.
For one column, I do not set any custom comparator function.
For the other column, I set a custom comparator function which is exactly the same as the default one used by Flex. (The private function SortField.numericCompare).
For both columns, I set the same data - 3000 Rows with values either 0 or 1.
When i sort on column1 (the one with custom comparator), the sorting is much slower than on column2 (default Flex comparator).
I went through the AdvancedDataGrid/SortField source codes but could not see why this could be happening as the comparator functions are the same in both cases.
Also, I checked out this bug -
http://bugs.adobe.com/jira/browse/SDK-13118
But shouldn't this be applicable to both custom and default sorting?
Can anyone help me out?

Answer 1

This is the function that i have : (same as the SortField numericCompare function which is the default function which is used if no customCompare is specified.)
        public function numCompare(a:Object, b:Object):int {
            var fa:Number;
            try {
                fa = _name == null ? Number(a) : Number(a[_name]);
            } catch (error:Error) {
            var fb:Number;
            try {
                fb = _name == null ? Number(b) : Number(b[_name]);
            } catch (error:Error) {
            return ObjectUtil.numericCompare(fa, fb);
As per bug, the performance should be slow for lots of items that have same value. But, it should be the same for both the custom compare and the default compare as the custom compare function I'm using is the same as what is used for Flex.