Quick Spell Speed Question

[Rongway]

Sorry for the long wait since "edit incoming"; I wanted to triple check my maths to make sure everything was good

Afair it's something like ~30 points per -0,1s recast

This number is off by an order of magnitude; it's closer to 25 points per 0.01s. But conceptually, your understanding of the marginal benefit is correct. Since each point is worth the same absolute reduction, the percentage of reduction goes up as points go up.

The faster you can switch from AF to UI and back the better. So, if you can get nearly 4 sets of AF off instead of 3 sets of AF that'd be much better than the normal right?
So in 90 seconds you'd be getting ~16-18 F4's instead of 12-14. Plus you also get extra room for bonus T3 procs. 390>280 [CR: did you mean >490? AFIII multiplier] even when not including the DOT.
When you have enough room for just 3 AF rotations extra T3 procs are sometimes bad. But if you have extra room, (like 10 seconds say) extra T3 procs are good because they're free damage allowing smoother transition to next full enochian phase.
Which is getting close at around 1100 SS.

Even if every cast was as short as the GCD and the GCD was, say, 2.30s, that's 26 casts per minute, and to fit in a 27th cast, it would require the GCD to drop to 2.22, which would require about 200 additional spell speed.


800 spell speed gives 2.79 Fire II/IV and 2.33 GCD
1000 spell speed gives 2.71 Fire II/IV and 2.26 GCD
and these numbers support a gain of about 1 cast per minute with a gain of 200 spell speed.

So in a perfect world where this one extra cast is a Fire IV, that's a gain of ~80 DPS, yes; but to cast that extra Fire IV realistically, you need an extra Enochian segment, which is at minimum an extra four casts (Blizzard IV, Fire III, Fire IV, Blizzard III), which is currently unattainable. (Note however that if this were attainable, it would be the Fire IV DPS gain plus the extra other three spells, so much more than 80 DPS. My point here is it's something to look forward to some day, but today is not that day.)