I found another computer and added remote access to it. It's a decently new computer with a relatively fresh install of Ubuntu Desktop, and I disabled the screensaver. The "Pause" screen comes up whenever the screensaver activates. I am using it now, and Firefox is the only (user) application running. It is working much faster. I also installed chrome on it yesterday, but the page auto-reloaded right after the first wave, taking me back to the beginning. Went back to Firefox, and Wave 1 took only 5-6 minutes, which is much better than over an hour. We'll see how it goes today. On the plus side, I have to remote windows open - one for the "dedicated" Attack on Altador, and the other for my "regular" Neo computer to do my normal dailies. It is working out well. Wave 2 in about 6 to 9 minutes. Not really tracking the time, just enjoying that it is working better.
Wish I could say the same about the PPT server. The issues are getting worse, and time to deal with it is limited.
ETA: With the newer computer, the latest game took only about an hour

However, at the end, it says... "Error! Something went wrong!"

However, this was my fault. Doing dailies on one computer while Altador is going on another computer.. logged me out of Neopets on the Altador Computer. Sure, the game keeps right on going, but... nowhere to send the score. Ooops. Live and learn. Here we go again...
ETA2: Completed the next game in about an hour as well... Got the Congratulations banner! Got the "Something has gone wrong! Please refresh the page and try again!" pop-up again. I have played and completed this smurf dung of a game 4 times to completion and have zero credit for doing so. Now I
am angry.

ETA3: I am not a quitter. However, I am very annoyed. Went back to try Chrome on the newer computer. Game definitely runs a bit faster in Chrome. Instead of repeating the insanity, this time, I clicked "End Game" during Wave 4. Score sent, Dead Void Beings were counted and reflected on that achievement. Next, I went for the DefeatVoid avatar, by Ending the game at the start of Wave 2 after one Voidling was killed. No avatar. But, did get 10 more points towards the Honorary Protector of Altador achievement. Maybe I typed too quickly?
ETA4: Played all the way through using Chrome. This time, it did not reset/reload mid-wave. And... No Error!! Received a Swift Darkfire Negg Bomb and the Clever Strategist Avvie. Finally. This game seems to have taken only about 40 minutes.
Confirmed. Played one more all the way through with Chrome. 40 minutes from start to finish (clicking fast forward through waves 2 thru 5's building phase.
I now have the Towering Defender Achievement. While 40 minutes still seems a bit slow, it's a lot better than 7 hours. I think I will be able to get the next achievement, and possibly the 3 in a row avatar tomorrow.
So... using Chrome appears to be the answer.
Seems like a good place to split this thread...
New Split is
here