I've certainly used patches with 500-1000 abstraction instances without problem, I guess I haven't tried 4600.
I wouldn't be surprised at all if the "limit" (i.e. the point where things begins not working) were somwhere between the two numbers.
I had a lot of problems with very big patches, and a lot of times things that worked perfectly fine with a "dimension" N stopped working with N+1, where by "dimension" I mean just the "quantity of things" (e.g. instances of a same abstraction), without the smallest change in "complexity". In some cases some developer (I won't tell the name, but it's someone very important here) was able to find specific bugs and fixed it and published a new release.
Unfortunately PD becomes somewhat unreliable if not unstable, when patches get really big. That's very frustrating, because the way it is 'defined' (i.e. the way it is supposed to work) really allows beautiful, complex, scalable design; but the implementation doesn't support it at the end. Also, these kind of bugs are very difficult to isolate.
The greatest frustration is when you carefully design something so that size (e.g. number of instances) shouldn't be a problem, you strongly test it within a certain 'size' and verify it is rock-solid, and then, when you have everything working and your project grows a little bit and you just add a couple more instances of something, it stasrts crashing....