The old read me file says that only 8 functions were changed so I took a look at one of them now:
Filter 1D array
Improvement when filtering every 5th element in a 100k array: 2.4x
Improvement when filtering every 100th element: 2.2x
Improvement when filtering every 1000th element: 1.8x
OK, but not that impressive...
However, looking at the algorithm I saw that there are repeated 1D Array searches for the whole array of elements to filter, that is costly. So I threw in a new alternative where that search is based on the sorted search instead. That makes a big difference when the number of items to filter is big, for the test cases above the results on my computer were
Improvement when filtering every 5th element in a 100k array: 227x
Improvement when filtering every 100th element: 22x
Improvement when filtering every 1000th element: 3x
Now the last algorithm changed two things, it uses both conditional indexing and sort/search sorted array. The sorting bit could just as well be added to the original revision...I guess the reason why OpenG still does not use conditional indexing is to be backwards compatible (very far now though...), and then the in-built sorted search would not be available either. That could be replaced by a binary search function that was available back then too though.
Filter 1D test.zip