Recommended specs will always be high. The minimum specs should be able to be much lower considering the 2D nature of the game, however because of serious limitations that are endemic to Construct's codebase, which are continuously denied but easy to spot just by looking at the engine code, that hasn't been possible. Even low resolution pixel art games stutter, and that's not just due to garbage collection.
It's simply not a tool for any sizable - or sustainable - game development, period, in its current state. Or seemingly in C3, based on the expectations of either a browser-based or wrapped-browser IDE, on either desktop or mobile, and certainly not on any console, marketing claims aside.
I'm not even sure the appropriate words exist in the English language to fully express the frustration I had getting even acceptable, let alone good, performance in Sombrero - and I've been dealing with web-based tech professionally for around 20 years. While I understand some (Ashley) will blame others for performance issues, that's simply not the case here - the engine just can't cut it for anything large, and definitely not anything that is meant to run at resolutions expected out of modern desktop games, 2D or otherwise.
Don't even get me started on collision (or often, lack thereof) issues, unstable frame rates, buggy native behaviors that Scirra refuses to fix (jumpthrough issues, for example), or missing features that are common enough that I can comfortably say they're available with any other option natively - and by "natively" I mean the actual definition of the word, not the one that Scirra misuses all too often to obfuscate performance issues that can be linked directly to C2.
Anyways, live and learn. There's other tools out there without these issues. I'd suggest looking into them. The event system is cool, but the albatross it's currently shackled to is held together with duct tape and bubble gum that's icky and gooey and the seams are showing.
Checking the spec required by your game it seems odd to me it requires so much. Me and my team mate work on a large project as well (check DinoSystem on Steam), which simulates a whole ecosystem with dozens animals roaming, eating, hunting, mating and doing their buisiness, hundreds plants growing, a dynamic weather system, seasons, thousand objects on the map. Still, the game runs fine on my mid-range laptop.
I agree C2/3 with html5/wrapper is not the more efficient engine to work on a large project, but still seems strange Sombrero needs that specs. Maybe its the destructible world feature or collisions, i'm quite curious about it and would like to know more.