The length of time it can take for your import to complete depends on a number of things, including your internet speed, age of your computer, or whether you're on a WiFi connection.
Other things that can affect your import completion speed are the number of records (rows) and the number of fields (columns) in your file. We recommend giving your import at least 10 minutes to complete.
It is unusual for gCast to 'stall' on an import and usually, gCast is working away in the background even though it may look like nothing is happening on the import screen.
Remember, you don't have to 'babysit' your import - by clicking on the 'send me an email' link on the import screen, gCast will send you an email when your import has successfully completed.