Howdy folks, I'd like to pitch in without getting confrontational.
I live in the middle of bumfuck nowhere and my internet speed is, at best on the best of all good days, 1.8 MB/s.
When people upload huge resolution pngs I understand it, alright, but it also makes the page take several minutes to buffer before I can continue browsing. This is even worse when I'm on mobile because it's even slower and I have a data cap of 500 MB a month.
I dared to browse Nebulous last week, now I'm out of mobile data.
Now, when you look at an image that has been compressed by a jpeg it's often not noticeably different to a png image unless that jpeg is either compressed and compressed over and over 'til you get artifacts, or the person who compressed it made it as small as absolutely possible.
There is a huge difference, however, between even a good-looking jpeg and a standard png, and it's very clear in file sizes. I can upload the same image, same dimensions, to somewhere. If it's a jpeg it might take me, say, thirty seconds. If it's a png it'll take me five to ten minutes. This is also heavily dependent upon image complexity, however, and I can make a jpeg a bigger filesize than a png under the right conditions.
In short, a jpeg is good for any sort of complex image. This includes photos, detailed artwork, and absolutely definitely poses. It groups together clusters of similar information and makes it less specific.
A png is good to show each pixel as intended, and is often a smaller filesize on simple flat-tone artwork such as, shown above, this one:
So what's the ideal solution?
Personally, I recommend deviantART which allows you to both cap your image at a set of reasonable dimensions and also offer the full png image as a separate download on the side of the screen, as an optional extra for people who want to view the full thing.
If you absolutely must upload it in its full splendour, which is lovely, can you post a smaller version with a link to your full-size one below it perhaps?
Personally I save everything in png format too because it does look objectively better up close, I end up posting a gyazo link here as it's less bandwidth though.
This is not an argument of elitism, this isn't something to whine about. It's just common courtesy and good internet etiquette to not press something that taxes those with poor connections just because they want to participate here.