gimp is like paint.net for people who arent scared of a mild learning curve and have 2 or more gigabytes of ram
first of all RAM quantity has nothing to do with loading time unless you have so little that it requires you to start using a page file
second, eat my richard

I've just installed it and opened it twice to check. the first time it took at least thirty seconds. the second, though, it took like three
presumably in practice it's going to depend on how long it's been since you last used it, whether or not you've installed any new fonts or anything like that, maybe some other stuff idfk
but the point is, it's not as snappy as pdn
also, worst of all, my favorite censoring tool ("crystallize" in pdn, "mosaic" in the GIMP) looks significantly less great in the GIMP