Optimize the WELD process for large number of objects

10,000 circles (halftone image) welded takes around 1.5 hours on my computer. It's insane, I know, and my PC is crap, but this isn't the problem. Taking the same elements at around 1000 pieces a round and welding them in chunks, then welding the chunks together into one takes about 7 minutes in total. The same result without trying to do all in one go takes a fraction of the time to achieve.

Clearly the welding process has some insane optimization problem that causes extreme delays that become exponentially longer with more elements for no valid reason. Please fix this.