Visual associations are a key part of many mnemonic systems. At first, making visual associations may feel unnatural, and it may slow you down, but keep practicing. The more you practice forming visual images, the quicker you will get. Creating visual images will always take a little extra time regardless of how fast you get, so it might not be the best strategy to use when the material you are trying to learn is being presented very rapidly. For material that you can learn at your own pace, using imagery will help. Even though it may take longer to go through the material once, you will need fewer repetitions and thus you will save time in the long run.