Slow running of a computer may be a result of an update to the operating system, drivers or the last-installed software. Other factors likely to reduce the speed of a computer include infection by a virus, conflicting programs loading at the startup, multiple security programs, third-party browser plug-ins and the accumulation of cluttered files over years.
When a computer runs slowly, it typically takes a long time to start, programs take too long to start or run, Web browsing is slow, and the Web browser takes a long time to start. To identify why a computer is running slowly, one must first determine when the problem occurs and on the nature of the slowness. If the computer is slow during startup while waiting for the appearance of the login screen, or if it takes a long time for the desktop to appear even after typing in the login credentials, run a virus scan to ensure that the computer is not infected. If a computer takes too long for the desktop to appear, or is slow when starting some programs, check for multiple security programs and determine whether several programs may all be trying to load simultaneously during the startup procedure.