Faster data retrieval in Autocomplete widget

Can someone suggest me ways to retrieve the data more faster in autocomplete widget and show it on UI ? The attribute is having around 25000 data to be shown as dropdown by autocomplete widget on UI. I tried using indexes on that attribute but it did not work out pretty well.
1 answers

Why would you want 25000 items in a dropdown? Will users really be scrolling through such a large list? I'd recommend only showing a limited number (100?)