Sludgeware is a way of describing software that sludges up one's computer with either unnecessary extraneous programs, actions or takes an unnecessary amount of time to load. Collectively, the repeated install of this category of software can turn the computer into a slow unfortunate system that resembles sludge. Sludgeware is the digital equivalent of the heavy mud that sticks to boots when tromping through the wilderness.
Those who have older machines and tend to use older browsers are more susceptible to sludgeware. Indicators of sludgeware include slow response time, and many search bars from third parties on the top of the browser window. Some sludgeware is unintentionally installed during the download of another product, and some is simply poorly-written software that is the only solution to a common problem available in a given market.