I got a message that my phone couldn't take any more text messages because I was out of storage. I checked storage and my apps were 9.02Gb (Galaxy 4S 16Gb). I drilled down into the apps and Contacts storage was 4.99Gb!!! I may have a lot of contacts, but I can't believe it is almost 5Gb.
That definitely is quite a bit for contacts storage! Are your contacts showing in the Internal Memory storage or in an SD card? Also, do your contacts have several multiples of the same number coming from different locations? ie Backup Assistant, email, Facebook, etc.