Yes, the effect was exactly as you expected, greatly shortedened towers. The game now also runs worldbuilder on slightly larger maps, apart from the few biggest ones, so we are making progress. The late game would still become taxing, as more units are there to animate and such.
As I'm not the one doing all the ungrateful work, I can't really say for sure, but it simply seems the game would greatly appreciate a more stylistic (as in, no actual individual drops, more heavens-to-ground dropchain) appearance. That, or more easily simply getting rid of animation altogether, so that all the drops are above ground, and possibly weeding the drop amount in half, making the rain more sparce (although this last one might actually work if animation is axed, giving that stylistic feel).
In either case, it is a shame, as this simply looks fabulous, and I'm terribly sad that this kind of butchering is necessary for (petty) practical reasons.