Incredibly Slow Restore

I’m using a My Passport external hard drive connected to a HP laptop with Windows 10. Took days to figure out why I couldn’t see the back up I did prior to a laptop repair, now that I have found it, the restore has slowed down to a worrying rate of about 1 file per 5/6 seconds. I started restore at 11am yesterday and at 6am this morning it was at 80%. At 8am it is 81%.
Is it normal to get slower and slower?
Anything I can do to speed it up?
Something I should worry about?