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This is not my experience. The apps have not changed with time but they do become more unreliable and slower after prolonged usage. When I first upgraded to ios5, everything ran fairly smoothly for several months.

Same experience here. When I upgraded to 5, the only problem was Safari constantly crashing. That finally became less of a problem, but over the past couple of months, everything has gotten really laggy. For example, I'll tap a text box, and it will take a second or two for the keyboard to pop up, with similar delays for each character to appear after it's been typed.

I agree with filmbuff that "2 years old is not nearly old enough for a device to slow down like this." I have zero interest in buying a new iPad.
 
Mine is getting pretty slow these days but not bad enough to upgrade yet. I don't use it much. Mainly as a recipe book while cooking and when I travel. For these, it still serves its purpose. I am starting to think about replacing it though. Maybe next spring when the next one comes out, maybe not. I just chalk the slow down to it being a first generation trying to run newer software with minimal power (mainly RAM).
 
First-gen user here, too. I use it as my primary reading device in addition to school (ebooks, notes, and Internet content provider during classes) Since my iPad will not be receiving anymore updates, I went ahead and jailbroke it. Might as well take advantage of the resourceful tweaks they have for the iPad and see if I can get something to help with its slowness. In iOS 5, the multitasking just brings it down to a crawl. I went ahead and installed Springtomize and disabled multitasking and spotlight. That means its back to iOS 3.2 functionality, but with the 1GHz chip, opening apps isn't as much of a pain, basically like opening programs on a pre-2011 MacBook or a PC. Not a problem. Plus, safari crashes less and apps are more responsive upon launch. Also, the multitasking gestures still work even with multitasking turned off, so you still have that feature. I also tend to use as many mobile sites and dedicated apps as possible as well as Reader. That cuts down on the RAM usage. I've found that sites with heavy ad placement brings the first gen down to a crawl with all of the JavaScript used.

Now that it's September and I don't have the cash to spring for the new iPad, I'll continue to use my first gen since it still works and gets good battery life and weigh the options later next year.
 
My iPad 1 has gotten very slow too. I've restored it, closed running apps, and rebooted it.

Certain apps use too much memory The iPad 1 only has 256mb of internal ram, compared to 512mb for the iPad 2 and 1,024mb for the iPad 3.

Many new apps are only being tested on more recent devices and need more of the internal memory. I don't think developers understand that their apps have a hard time working with limited memory.

For example, I play a game called Carcassone. It must be the ONLY app on the system for it to run properly. I must close all background apps, wait 10 seconds for the memory to clear, then start Carcassone. Note that every app takes a certain amount of internal memory to run in the background (some of the 256mb). Some apps take a lot more than others. And when you close the background apps, iOS sends a signal to that app to kill itself, and the app has 5-10 seconds to comply with the request, so you do need to wait 10 seconds.

Same thing for Safari if I'm on any memory intensive websites, or the USA Today app.

It's just what we have to deal with when using old hardware. I'll be getting an iPad 4 when it comes out. Just another 6 months or so with my old reliable iPad 1.
 
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