User blog:Ar-cen-ciel/Caching Kanmusu Sprite Files

About the Kanmusu Sprite Files
The Kanmusu Sprite Files I'm talking here are the files that contains the character sprites for the personification of warships (mainly from IJN, as this is a browser game from Japan). Most of these Kanmusu sprite files are fairly large, typically at around 300-500KB (kilobytes) per character/file. This is because these files contains a set of character sprites instead of one so the servers doesn't have to download the images mid-battle and ended up with missing sprites due to slow Internet connection.

Whenever you meet a Kanmusu, either from sortie drops, construction, or from viewing other player's ship girls, the game will request their character sprite files. In the context of browser requests, the browser cache will be searched to fulfill the request first. If it's unavailable from the browser cache, then the browser will forward the request to the Kancolle Server. This means that the game will request the character sprite files when you saw them for the first time since the last cache clearing.

After the file is downloaded once, the sprite files are stored into the browser cache like the rest of the game's assets and will be referenced whenever the file is requested again. This gives the player a smoother gaming experience and significantly lower bandwidth cost for both sides from the game. To put it in perspective, an average player would accumulate approximately ~200-300MB's worth of download/cached data throughout the normal caching cycle just for Kantai Collection alone, which contributes to a significant portion of Kancolle server's bandwidth usage (and your data plan's quota too, if you have any). This is the main reason why constant cache wipes or otherwise non-persistent browser caches are frowned upon by Kancolle's developers.