Temps dictate grow rate for mine to a large extent, it's been well below normal here too and on cool days growth is negligible, on days that are hot there's growth, if we get a 2 day stretch of warm weather that includes a night above 65 and highs around 80+ it moves alot faster!
I've never experienced weather quite like we have had this summer before, atleast not until much later in the season!
Those blooms really seem to drain a Thai big time, more than other colocasia, but most colos don't ready throw 6 blooms at once, most of mine throw 1-3 blooms per site, increasing to 1-6 blooms per site with age, and daylength decreasing, Thais start out with a flurry, I liken it to a week of marathon love making, which can take a toll...and drain even the most vigorous...
Mine seems to be setting seed, that can't help with leaf growth rate...
I've spotted a few Thais planted out near me, I doubt the owners know what they even have, one of there's is tremendous and has yet to bloom, it makes me wonder why it hasn't, it's massive, certainly not a 1st year plant, and growing in FULL southern sun.
I feed mine very high P and VERY low K in hopes it wouldn't induce blooms, fail... Next year ill try one with high N and P with low K and another in very rich compost and little fert, to see what happens...
And of course ill have to knock on these people's door and chat em up to see what they do, and if they have any idea why some of their EE are monsters and the rest( plain C. Esculenta) are just big... I bet they have no clue!