If you look at the Pages read from disk/sec metric in Athene or the Memory:Page Reads/sec in Performance Monitor, a consistent figure above 5 usually indicates a memory bottleneck. You may have increased the Memory in your NT system but it still appears to be causing a bottleneck. When memory is the bottleneck, check what the internal cache is set to if it has been set. Secondary cache is used to provide read-ahead access to RAM. If you add RAM without increasing the secondary cache, lower cache usage can result. This causes the secondary cache to attempt to provide caching for a larger amount or RAM. Check the OEM specifications