When Google Instant was launched, many power users noticed that they need to press Enter after typing a query that included advanced search operators like site: and filetype:. Most likely, these queries are resource intensive and it's difficult to return the results very fast.
Now you can use these operators without having to press Enter or click the search button. The main advantage is that you can adjust your query and see the results as you type. Unfortunately, the results aren't displayed instantly.
The Serial Swatter
8 hours ago