Good job, I got 15/18
I find that with things like this my distribution of times is extremely uneven: I get most words in a few seconds, but every now and then one comes along that for whatever reason my brain doesn't want to see and then it takes much longer. (And if that "much longer" is over the 30-second limit, too bad, I lose.)
And something about this makes playing with the timer annoying for me: I feel some combination of "surely I should get some credit for getting all those others so much quicker than the timer allows" and "oh, come on, that was just unlucky and doesn't reflect what I can generally do".
(I am not claiming that it's right to feel anything like that. Just that I do and I suspect I'm not alone.)
I wonder about a mechanic like this: the timer starts at 30 seconds; when you solve a word, rather than resetting to 30 seconds the timer increments by 10 seconds. So if you're solving in <10s on average then (at least after the first few, easier, words) you can afford to have the occasional brain failure without getting thrown out of the game. And your overall performance depends on how well you do on all the words, not how you do on the single worst one.
(I agree with others that there should also be a no-timer mode for those who just don't want to feel tested and/or stressed in that way.)