Complex sentence: However, when looking at the life-cycle of expert systems in actual use, other problems--essentially the same problems as those of any other large system--seem at least as critical as knowledge acquisition: integration, access to large databases, and performance.
Split into simpler sentences: However, when looking at the life-cycle of expert systems in actual use, other problems seem at least as critical as knowledge acquisition. These problems were essentially the same as those of any other large system: integration, access to large databases, and performance.