Over the past 15 years, capsule endoscopy has been an important tool for the examination of the human gastrointestinal (GI) tract. Compared to traditional colonoscopy and gastroscopy examination technologies, capsule endoscopy is able to examine the GI tract more effortlessly and smoothly, including the small intestine which was formerly unreachable. While the small size of the commercialized capsule endoscopy makes it easy to swallow, it detracts from the efficiency of the imaging device inside the capsule and does not allow for the inclusion of an internal locomotion device, leading to limitations such as low image resolution, passive capsule movement and low power source capacity. Research has mainly focused on developing: locomotion and powering mechanisms; an algorithm for view time reduction; or image compressor simplification and complexity reduction. This study aims to provide researchers and engineers with the drawbacks of the existing studies into improving capsule endoscopy efficiency. The current study has addressed a number of limitations associated with the methods proposed previously for each of these research trends and suggest further investigations for improving the capsule endoscopy technology for better diagnosis of many concerning diseases related to the gastrointestinal tract. This survey paper not only identified the technical limitations in existing research but also classifies studies to aid the understanding of engineers.