The jAlbum uploader should, indeed, upload only new or changed files. Make sure you're not doing something that results in all-new images being created, like choosing Force Remake.

After making the album, but before uploading it, open the output directory and take a look at the time stamps on the files, especially those in the slides and thumbs subdirectories. If they're "new," you must be doing something to cause that, like changing image bounds.

I suspect David will be in touch. We've seen one or two reports of this happening, but have never been able to reproduce it, so the cause is very mysterious. All the more mysterious, as it appears that you're hosting on jalbum.net. That rules out a bunch of the usual suspects.

Hi
Okay, so I did as you suggested and clicked the Make Album button and then the Upload button with no additional images added since the last time. No problems, the Make Album and Upload were done in seconds.
I then added two images to one of the folders, they are 472 kb and 459 kb in size and clicked the Make Album button. It took seconds to process, I then clicked the Upload button and I am into a full upload of the complete album, 47.7 MB in total which did not seem to take as long as last time but it wasn't obviously just the two images being uploaded.

Also bear in mind that if you're using a JSON-driven skin, like Tiger, it's not just the two new images that have to be uploaded. Because there are new objects in the project, the JSON files for the album will also be new, and will have to be uploaded. These might be quite large if the project is a big one.

ETA: And there's also a new lifeboat file, which will also be fairly large for a large project. Don't succumb to the temptation to turn off the lifeboat file - that's a decision that will come back to haunt you.

Can you pass a link to the uploaded album?

We've just been trying to rule out the usual red herrings.

I have a large family album with almost 5000 images and videos. When I add a few new objects, the album build takes under 30 seconds, and the upload takes even less time than that.

What you're describing has all the earmarks of a hardware problem. I've seen it myself. I was once experiencing terrible uploading problems, and was blaming my web host. But getting a new cable modem cured it instantly. Downloads were fine, but uploads were a disaster.

Just recently I found that I wasn't getting the upload speed my ISP was promising, and that I had been getting with no problem until recently. Album uploads seemed to stall part-way through. Long story, but it turns out the Ethernet port on my PC is defective. As with the cable modem, downloads were find, but uploads were grinding to a halt.

Time to do some debugging. ISP's are usually amenable to swapping out the cable modem, as long as it spares them from having to "roll a truck." See if they'll do that.

If your PC is hard-wired to the router, try using WiFi instead (that's what's getting me by at the moment - it's slightly slower than a direct Ethernet connection, but good enough).

Thanks for providing the album link. I now think I know why it takes so much time, even if you only add 2 images:

You have "Album Settings - Tiger - Site - Download - Offer download as ZIP for" set to "Originals". This causes jAlbum to produce a zip file of all original files. It's probably the uploading of this huge zip file that causes the slow uploads. Perhaps you can consider only offering a select few images for original download OR the scaled down images only? The options are there.

Here's how I discovered this:
1) I opened a dummy project within jAlbum
2) I selected File->"Import->Settings from published album"
3) Now I hit CTRL+SPACE and typed "download" to be taken to the download options of Tiger (faster then navigating manually)
4) I now saw that this option was set to "Originals"

There is another workaround for this, and that is to break up each sub folder to individual galleries. You can now add new folders without affecting the zip files of each sub folder. Make the "top level" gallery using "web locations" that points to each sub folder.