I looked at the website and it's marketed a bit as a race bike. Like the European norm it's passed is used as a standard for normal non-competition race bikes. But for $1200 you can't expect too much out of it. 20 mph is already a very decent speed, like I don't really expect this thing to be able to hit 30 mph, but going 18 with some city bikes is already ehh...
It can definitely do 30mph on a flat if you have the quads for it. I got to 26 today on a tarmac sprint without bursting a blood vessel and I'm old and out of shape. It's fitted with quasi slick but fat tires. On a narrower set (which those Mavics will happily accept) you'd get significant gains - and with drop bars, a little more still just from aerodynamics.
When I get home, I'm putting a set of gravel road tires on it because I want it to be a bit more multipurpose, but this trip was a great way to check it out from home to airport to destination. On that score it's fantastic - the folding process and unfolding is all tool free and takes about the same 60 seconds as a Dahon or Tern. TSa rummaged through the bag because I put sleeping bags in with it for the trip - but they were also handy padding over the discs and hub.
Even reductively, if you spent the same amount on a focused, purpose built road bike or racing bike, you'd probably get at LEAST two or three hundred dollars more bike - which could mean a serious component level upgrade, or even a cheap carbon frame. If you don't want to travel with it, or have serious space constraints at your home, this is not really a sensible consideration.
But again, if you can ride a bespoke, purpose built bike of the same weight and geometry and configuration at xx mph, there's nothing about the latch mechanism that will affect your ability to approach or match those speeds. I assume there are geometry issues (good or bad) that will make a bigger difference on the MTB versions and it has a slightly lower stem/crossbar that reminds me of GT's old geometry.
They have four main styles - a "rugged hybrid" which is what I have - a hardtail MTB with Fox front shocks, a 700C (what I'd call a) hybrid and there is a race configuration of that and the hybrid, but it would make no sense for a serious racer - it's very strictly targeted at people who have space limitations in their house, or people who want to travel with a "real" bike - or people who want a folding bike that can be fitted and customized with standard components. Even bottle cages fit on it, which was surprising given the placement of the folding mechanism.
I have a Cannondale Quick 2 Carbon as my main road bike, and a newer Trek hardtail for trails and the wilderness, and this Change bike can't really match them, but it's not supposed to. But there are probably a lot of "serious" cyclists who could use something like this at a logistics level as a trainer/vacation/commute solution. But for my very specifc needs - this has way exceeded my expectations so far. Doing a 50 mile loop tomorrow and some more tooling around on dirt this evening when I finish some work stuff. One other very specific solve this has for me is road trips where our family takes three bikes - I have a tow hitch bike rack that's
supposed to take three bikes, but it's kind of a Jenga problem with the smaller frame on my daughter's - so we sometimes take my folding bike and just mount their two on the hitch. This just lets me take a "proper" bike in the trunk of a small sedan without disassembling it.