Protip: get an SSD. It improves your life in many ways. Three examples I notice between my girlfriend's HDD-based laptop and my SSD-based one:
- A game, Factorio, takes literally 5 minutes for her to get to the main menu. For me it takes about 30 seconds.
- Using `time gimp` and hitting alt+F4 immediately, I get about 2.14 seconds. For my girlfriend this indeed takes a little bit, though not a minute.
- Booting up (from cold) is maybe 20 seconds for me. For her, this takes more than a minute on Ubuntu and more like 2-3 minutes on Windows (it boots in the same time as Ubuntu, but then programs need to load which make it slow for another 1-2 minutes).
Not everything benefits from it, like web browsing or email is not I/O-bound, but lots of things go a lot faster for the investment. Especially for laptops, it's also quieter, supposedly uses a little less power, and won't die as fast from dropping it. I'd highly recommend it.
I'm not putting off your computer as being the blame for GIMP being slow - indeed, it's kinda silly that it takes so long to start, especially the first time - but I just figured you had an HDD and think the vast majority of people will benefit from an SSD. Even my grandma got one a few weeks ago and is super happy with it.