Spiders are apparently poikilothermic

hmm

that's a hard one

you could probably make a case for either

wait and ambush is a strategy used more by poikilotherms

they have to eat less than a mammal

a big animal also loses heat more slowly, so it could be done

But they tend to be slower moving

less mitochondria, less energy output

even in spiders. little ones run all over the place. big ones are more deliberate, though they can run

hmm

you could also make a case for something halfway in between

partial heat regulation, offset by behavioral maintenance, ie basking somewhere warm

still a little sluggish when it's cold, but not completely catatonic like bugs get when it's cold

if you want something fast and deadly (or as deadly as jowan is, anyway) endothermic might be the way to go

a big poikilotherm is going to have to be very deliberate with its energy usage. slow, careful. it can be done, but it's a different approach.

the trade-off for being an endotherm is being really really super efficient, but only at one temperature so you have to spend energy keeping yourself there

vs. poikilothermic, where you're not so efficient but can operate at a wider internal range

so I'd say it depends on what sort of end result you're looking for

You are so cool

for a certain value of cool

and if you define "36.4 C" as cool

which it is, compared to the average body temperature

omg