a restore CAN make your phone warm up while it processes everything. It tends to do a lot of background processes.
as for whether to do a restore or not..... some say it's fine, others say you should never do it. Me, I restored twice. Considering my "backup" originally started on a 920, then an 830 and then my 950, what i did was do a restore, once it was done (3 days later!!! txts took FOREVER the 1st time) i deleted the backup on onedrive, forced a backup on the phone (which created a new backup on onedrive) and did a hard reset followed by another restore. no issues beyond what seems to be the standard 950 issues and I have all my data/apps/setup.