First note that the progress bar is pure guesswork. Don't read too much into the percentages. Doing a restore involves many different tasks, and how long each one will take varies a lot depending on what is in the backup file. Moodle does not try very hard to guess how long each task will take. I think it allocated a fixed percentage of the total to each task.
And, from various reports, it seems to assume that restoring questions will take 2% of the total, which is clearly not true in this case, but that's life.
Anyway. I don't think anything changed in regard to restoring questions in 2.6. I just searched the tracker to make sure, and that confirms my memory. Other parts of backup and restore were improved.
There is an outstanding issue about improving the performance of this part of the code: MDL-39726. The good news is that Eric Merrill has just picked up the work that Russell Smith started some time ago, so fingers crossed it might get fixed soon.