Yeah, wow... Just typing down here, clicking on the game and waiting a while, then resuming... halfway through the next run it just stopped responding to clicks at all unless I spammed them. Barely got through that segment to the end of it. Hopefully a non-browser version will have that ironed out, but that's a major issue if it will do that when switching out of it. :/
:edit: Strangely, however, the next segment sped by at a normal clip despite typing this down here... and the ying-yang should not have triggered (no gold modifiers) but it game me bonuses )the effects of blast and guardian) and exactly what I needed to compensate for the temporary hiccup in clicking, which didn't last as long the next time.
Thankfully, with that being the end of the demo, I didn't see the random modifiers with ying-yang happen anywhere else, and elsewhere the lag was minimal. Just that last battle that had the worst of it, and the only one I had to redo after learning the mechanics.