3-4 seconds is very fast for a restore. And one reason it's fast is that they are cheating a bit, and which you should be aware of. That is, the transaction log is thrown away and replaced with a new file of a mere 500 KB. So do the operation properly, you should immediately grow the log to a reasonable size. And, yes, since the log file has to be zeroed out that will be a few more seconds.
How big is the database in question?