Improves performance when Virtual Memory is turned on in the Memory control panel. Power Macintosh 5500/225, 6500/225 and 6500/250 users who have upgraded from System Software 7.5.5 to Mac OS 7.6.1 via the Mac OS Up-To-Date program should check to see if they have the extension in their System Folder. Power Macintosh 5500/225, 6500/225 and 6500/250 users who do not have these extensions, should install the 5500/6500 Extras Update. Current Power Macintosh 6500/225, 6500/250, 6500/275 and 6500/300 pre-installed with Mac OS 7.6.1, already include these 5500/6500 Updates. These users do not need to install this Update.