I just had the opposite problem in my last game. Vanguard/Quadratic - First waves were easy, last was hellish. There was well over an hour between the last two waves, but the final wave's strength was over 50,000 Str vs 2000 Str for the other AI. All Guardians. I'm glad I finished the game when I did, the next wave would have been truly nasty.
Talking to myself here... I went back and re-checked that log.
By "well over an hour", I apparently meant "Over 5 hours". And while 50,000 Str is a lot more than 2,000 Str, the 2,000 Str waves were coming every 10 minutes. The next Quadratic wave would've been Strength 100,000 - but it wouldn't have arrived for almost 10 HOURS.
That means a Quadratic AI player will send 10 waves in 50 hours of game time, roughly (AIP dependent). Total strength of those waves will be 200 * (2^10 - 1) = 200 * 1023 = 204,600 Str.
The normal AI, in the meantime, sends roughly 300 waves, totaling about 5-600,000 Strength.
So, while the individual waves of the Quadratic AI are nastier after the first, they take SO long to come that the overall strength sent is about 1/3 that of a non-Quadratic AI.
Soooo... I think Quadratic may need a buff.
I think I might have to science out Quadratic though... I wonder if I can get it to crash the game with a massive wave >D
Unfortunately, according to the logs, the Quadratic is capped at 10,000,000 Strength per wave - AFTER multiple HW, Difficulty, and Handicap checks. That'd be the 20th wave, which will arrive between 400 and 600 hours after the 19th wave in a 16 homeworld game. In a 1 homeworld game, it'd be around 13 months.