To optimize Firestorm, you need to remember to clean your cache periodically. The more frequently and longer times you spend in the virtual world, the more often you need to do this. 

Your browser cache will need to be cleared frequently. 

You will also want to clear your logs. If you don't want to delete the old logs, create a new folder. These files get very large; you will need to move these old log folders to another drive. Otherwise, just clear the existing folder.