What can cause big data being slow?

Companies operating in some areas can gather all the data they need with relative ease, more specifically marketing companies, social networks or internet companies to name but a few. However when it comes to analyzing these data, many problems may occur. Insufficient resources that can store all this flood of data or highly significant response time to get the results. In some definitions of Big Data, one of the main characteristics is Velocity as the results should be obtained quickly. This is why optimization is a top priority while working in a Big Data environment. In this paper we provide a state-of-the-art report of the main causes of performance related problems in a Big Data environment. Our study is mainly focused on Hadoop as it is free and the most popular solution when it comes to Big Data.