Restoring backup course in Moodle 2.6 takes considerably longer than in 2.5. Even modest size courses (30 - 40MB) take 20 - 30 minutes to restore. Occasionally there is no confirmation message that the course has actually finished restoring.
Based on previous experience backing-up and restoring courses of this size, I would expect the process of restoring to take about 3 - 4 minutes.
To replicate this problem, simply backup and restore a course in 2.6.1.