Several readers have mentioned deteriorating PC performance and have asked for an explanation of why a PC that is a year or two old performs less well than when it was new. Frankly, we didn't know, but we got the answer from someone who is an expert in the Windows operating system. The problem relates to how programs move in and out of Windows.
A program consists of many chunks of programming code called DLL files (dynamic link library) which are stored in Windows system directories. When a program is installed on a PC, a set of instructions is loaded into the Windows registry file. These instructions tell the registry, and therefore Windows as a whole, when and how to run the soft-ware's DLLs. When many instructions accumulate in the registry, the system begins to slow down.
Then a program is uninstalled, these DLLs are usually left behind. Performing the uninstall procedure, the user is alerted that a file may be used by other programs and one should consider keeping it. After receiving this advice, the user tends to respond cautiously to the "keep/discard" decision. If one says "yes," and the DLL is not used by any other program, one has created an "orphan DLL." These consume computer resources and, therefore, slow the system.
The best solution is a registry editing program that automatically checks and edits the system registry. These registry editors work by scanning the registry and looking for DLL files that no longer do anything useful. They then prompt the user to delete these files. The most widely used are Symantec's Norton Utilities 2000 and Mijenix's Fix-It Utilities. Each is available for Windows/95/98 at a price of $50.
The products are available at most computer stores or can be purchased online from the respective companies.