Append table cells to select boxes in indexed order
First little thing: var names are important. So 

var option = '&lt;option value="'+text+'"&gt;'+text+'&lt;/option&gt;';


Second and main. When we are making webapps with JS, the main perfomance rule is: 

Reduce access to DOM  

I tried you code with 15000 tr's in Firefox and Chrome. I wrapped you code with

console.time('DOM');
...
console.timeEnd('DOM');


Results was:


Chrome - about 5000ms 
Firefox - about 20000ms


Then i replaced $.append() with just strings concatenation

console.time('String');
var itemOptions = '', valueOptions = '', propOptions = '';
$('tr td').each(function() {
    var $this = $(this);
    var text = $this.text();
    var option = '&lt;option value="'+text+'"&gt;'+text+'&lt;/option&gt;';
    switch($this.index()){
        case 0:
            itemOptions += option;
          break;
        case 1:
            valueOptions += option;
          break;
        case 2:
            propOptions += option;
          break;
        default:
          alert('Unexpected Error.');
     }
});
$('#item').append(itemOptions);
$('#value').append(valueOptions);
$('#prop').append(propOptions);
console.timeEnd('String');


Results:


Chrome - about 1100ms (bravo, Chrome :))
Firefox - about 4000ms


If you will change your data source to a JSON or something, next optimisation will not need, but you can set first argument of .each() method (index of all td elements) to avoid using .index(). I noticed about 300-500ms of speed increase. So the last version is 

console.time('String');
var itemOptions = '', valueOptions = '', propOptions = '';
$('tr td').each(function(index) {
    var $this = $(this);
    var text = $this.text();
    var option = '&lt;option value="'+text+'"&gt;'+text+'&lt;/option&gt;';
    var modulo = index % 3;
    switch(modulo){
        case 0 :
            itemOptions += option;
          break;
        case 1:
            valueOptions += option;
          break;
        case 2:
            propOptions += option;
          break;
        default:
          alert('Unexpected Error.');
     }
});
$('#item').append(itemOptions);
$('#value').append(valueOptions);
$('#prop').append(propOptions);
console.timeEnd('String');


Results:


Chrome - about 850ms
Firefox - about 3500ms