Pretty sure they always go minimum speed which is a pity, makes accel completely pointless and adjusting speed a hassle of adjusting min and max to increase min speed by one.
Currently going from T59 -> T60 and it took me less than 5 minutes to get a petal (Admittedly, a bit on the lucky side on that one), but it does not really take that long even at higher tiers to move up by only breeding. (And there's the altar option for mutations for the impatient!). Just be a bit patient, do something else for up to half an hour and then after you get the first petal, you will get that one petal into different positions quite fast :)
Here's a setup that might or might not inspire someone:
http://snag.gy/NL5PH.jpg
Replace fans with T5 ones, the cells with single Nefastium, and higher reflector ones. With only the first nefastium base power upgrade, and 4/6 heat upgrades.. running the setup at 100M/109M heat, you'll get ~304 mil / tick. (You won't be able to sell that fast unless you have the last capacitor upgrade though.)
The newest patch seems to be bugged. With a Single Nefastium Cell (2.893 Mil heat) surrounded by 4 x Coolant cell (Taking 723,25K each), linked into 2 heat exchangers each (925,92K of exchange) linked into fans that have more than enough ventilation, it just causes the coolant cells to rapidly fill up when the setup should be able to take care of all the heat.
Picture of my old stable setup. Once finished you can easily run multiple double doloriums. (This setup cools down faster than it generates heat, and has enough transfer by far to not need to replace the cooling tanks.)
http://snag.gy/492sc.jpg
A very enjoyable game! Currently waiting so I get to test some theorycrafted setups involving few but high-end fuels. Depending on how stable you want to run and how many schenanigans you want to use it makes a huge difference. If I'm not mistaken, a multiple Double Dolorium (5-6+?) -set should be runnable stable without using the reactor as a means of transfer. A Quad Dolorium or a single Nefastium (probably two single nefastium?) should be able to be stabilized with reactor taken advantage of. Double/Quad Nefastium setups I couldn't come up a stable solution for with yet, probably not possible with the state of current balance. (I consider stable as something you can leave running without worrying it'll blow up. With coolant abuse even these are possible.)
Hm. The difficulty of survival should ramp up in some other way. I got 43344m, and everything is flying by so fast I basically have to spam jump and stay offscreen. It even gets pretty impossible to try to snipe a health upgrade or a tesla gun at that point. But it was a fun play.
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Can you send me a screenshot? I can't seem to replicate that on my end.