Is this what you're seeing or what they are seeing? Anyway do you have like 50k sms and mms from every conversation you've ever had with everyone? You might try reducing that number and getting rid of stuff that isn't important anymore. Then go to your SMS app(s), both the stock/native app and the third party app you use daily and clear the cache for both. You could use a cache cleaner like CClean if you wanted to, but a lot of times restarting your phone a couple of times will clear out most of your caches too.