BLOB cache needs to be enabled in the front end web server(IIS) and once configured; the frequent files used in sharepoint will be retrieved from the database and stored in a directory under Front end web server (IIS). This reduces the network traffic/load on the database server as the frequent files will be stored into disk .Got to WebApplication web.config file search for <BlobCache>
<BlobCache location="C:\BlobCache\14" path="\.(gif|jpg|jpeg|jpe|jfif|bmp|dib|tif|tiff|themedbmp|themedcss|themedgif|themedjpg|
themedpng|ico|png|wdp|hdp|css|js|asf|avi|flv|m4v|mov|mp3|mp4|mpeg|mpg|rm|rmvb|wma
|wmv|ogg|ogv|oga|webm|xap)$" maxSize="100" enabled="false" />
<BlobCache location="C:\BlobCache\14" path="\.(gif|jpg|jpeg|jpe|jfif|bmp|dib|tif|tiff|themedbmp|themedcss|themedgif|themedjpg|
themedpng|ico|png|wdp|hdp|css|js|asf|avi|flv|m4v|mov|mp3|mp4|mpeg|mpg|rm|rmvb|wma
|wmv|ogg|ogv|oga|webm|xap)$" maxSize="100" enabled="false" />
