Nearly all applications on your Mac, especially ones made by Apple, have cache files. These cache files contain data to help your application run quicker and generally faster. For example they cache data which is used often so it doesn’t have to be calculated. Thats what cache files do. But these cache files get bigger and more bloated. As a result they can actually slow down the application, since they may contain data that is not needed but is still being read. It is easy to delete a cache file and let the program make a new one.
To find you cache location open a new Finder window and navigate to /Users/James/Library/Caches/ this folder contains a lot of folder which contain your cache files. Simply located the folder of the application you want to delete the cache file. And delete the file. Make sure the application cache you are deleting is closed before you do this, to make sure you don’t corrupt anything.
I deleted my Mail cache file, since Mail was acting so slowly. When the application was restarted it opened instantly rather than waiting the couple of seconds I had to before. Instant improvement. I don’t recommend, mind you, deleting every cache file you have. This could cause problems. Only delete the cache files you are having problems with.