Selectize.js

Performance

This shows how it performs with 25,000 items.

// <select id="select-junk"></select>

var letters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUV';
var options = [];
for (var i = 0; i < 25000; i++) {
    var title = [];
    for (var j = 0; j < 8; j++) {
        title.push(letters.charAt(Math.round((letters.length - 1) * Math.random())));
    }
    options.push({
        id: i,
        title: title.join('')
    });
}

$('#select-junk').selectize({
    maxItems: null,
    maxOptions: 100,
    valueField: 'id',
    labelField: 'title',
    searchField: 'title',
    sortField: 'title',
    options: options,
    create: false
});