To find an item in a skip list start at the highest level and check to see if the key is greater than the first item in the level. If not, drop one level and repeat. Once the key is greater simply follow the chain. A secondary advantage is that the coding for inserting and deleting keys is minimal compared to B-trees. Some background on virtual memory systems is appropriate at this point as testing showed it to be a dominant factor in performance.
Storage is done in blocks of memory called pages.
When a program requires a page of memory that is stored on disk the computer must read the disk. This is immensely slow compared to accessing real memory. This slows down the computer considerably. In our case it is related to how many pages the algorithms must access to find a particular node. Complexity B-trees are an extremely popular method which makes for interesting reading.