The problem with 2000I is that is single threaded. I used it for many years, but because of higher volume and more transactions the single thread software started to lag. Even a fast processor could not compensate the problem. Calculations were sometimes 10-20 seconds behind. I had to replace it with NT7.
Because when it was written there was still no multicore software. Everything had to run on a single core. It worked good till volume grew. When it was introduced it was by far the best program you could find.