I would suggest using Nichrome. People having issues with claptons ramping up on even their mech mods have switched to Nichrome from kanthal and seen faster ramp up time.
Yeah. Personally, I prefer nichrome for my tube mods, but I don't really like the performance of those too much. They're harsh and the flavor/vapor just isn't up to par with what I can do with kanthal on a series or regulated mod. It's all very vapable and better than standard coils in many ways, but I've never done anything that wasn't inferior by clapton standards.
I do occasionally use nichrome for the outer wire with kanthal for the core. Whether or not this is a superstitious practice, I couldn't tell you. I'm not entirely convinced that nichrome heats up all that differently from kanthal. Any difference from kanthal would be due to density and heat capacity, since the outer wire is basically inactive, electrically.
Claptons are generally power-hogs. They pretty much always need more than natural voltage (4v) to get there. Even a high-current build needs more power than it can get on a 4.2v mech because the outer wire has so much mass to it. The ratio of mass to power needed doesn't change with the amount of current. Standard mechs are harder to match a clapton to. It can be done, but your options are very limited. You have to keep the coils pretty small for the amount of current they pull. They're not ideal.
And then, on the flipside, if you use a regulated box, you still have to watch the mass of your coil. If it's too big, the heat-retention will be through the roof and the coils will quickly overheat from the wattage it takes to get them going. If it takes a long time to heat up, it'll take at least as long to cool down. And if you pump extra voltage to it, then it will get that much hotter that much faster, but it won't cool down any faster.
So it's sort of a balancing act. Everyone has different tastes, vaping habits, and combinations of gear. It takes some trial and error. Ask any clapton user and they will say that it's worth it, but none of them will deny the fact that they are finicky bitches. Once you get a feel for how different parameters affect performance, it's easy to tweak and intuit the kinds of builds that will get you what you want, but you're probably gonna do a lot of throwaways to get there.
But hey, at least by then, you'll have the technique down to the point where you can make clapton wire without looking.
One thing that will always help with speed and reducing heat retention is using thinner outer wire. Personally, I go with 36g and smaller. My favorites for pretty much any clapton are 38g and 40g. I find that they get more flavor and much more of that dense, chewy texture. The difference in speed is night and day, too. They're much more efficient and still carry all of the benefits of claptons with thicker outer wraps. I think it's a good compromise.
You can also use thinner cores and parallel them in a fused clapton. Two strands of 28g have different heating properties than a single strand of 24g. The individual strands transfer heat much faster, allowing you to squeeze in similar surface area to thicker wires and pull about as much current without as much ramp-up or overheating. It just doesn't have to get as hot to perform.
You could always do singles, too. Lots of clapton users do. They're not like standard singles. Clapton singles can have every bit as much surface area as a dual, but because of their unique wicking and heating properties, they can be very MEAN and yet, very balanced.