One of the most significant advantages of OCS Inventory NG comes mainly from its performance. The inventory for every machine is really lightweight thanks to its XML syntax. It requires little-to-no CPU processing power. This way, it does not put any load on most of today's processors. However, in the case of large environments, it needs a relatively beefy server with a big RAM size.
Keep in mind that the software was designed in 2005. Back then, most mid-sized enterprise servers had around or less than 3GB of RAM. We should not forget about the 32-bit limitations as well. The official documentation states that when working with inventories with as many as 70,000 clients, they needed 3GB of memory. They also picked a distributed setup that spread across 3x 2.8GHz Xeon servers.
Nowadays, one new generation server can cope with such a similar load, assuming it has more or at least 4GB of RAM—preferably 8GB. But if we dedicate such a workhorse power...