Perhaps this will help you understand OS X memory usage a little better:
all memory in OS X is "virtual". Some of that virtual memory is in RAM, some in system and application files on the hard drive, and some may be in swapfiles
Wired RAM is memory that is pernamently "locked" by the OS and cannot be made inactive or moved to swapfiles. It must be there for the operation of the OS
Active RAM is memory that is currently in use by either the system or an application.
Inactive RAM may be thought of as a first stage swapfile. It contains instructions and data that are not currently in use within the OS or an application, but is left in RAM in the event it is needed again. If more Active RAM is needed, the Inactive RAM will be reassigned and if it contains data for a currently open application, that data will be rolled out to a swapfile. Otherwise the memory will simply be overwritten.
Free RAM is just that. It is RAM that is currently not mapped into Wired, Active, or Inactive RAM. If more Active RAM is needed, the Free RAM will be the first to be remapped into Active status.
Swapfiles are used to contain data being used by currently open applications for which there is currently no room in either Active or Inactive RAM
System resources, fonts, application files, frameworks (shared libraries) are mapped into the virtual memory address space for each application whether they are in Wired, RAM Active RAM, Inactive, RAM, or in files on the HD, but these resources are never placed in the swapfile(s) because they are already available on the hard drive and there is no point in duplicating the code.
Pageins occur anytime something is moved into Active RAM whether that is from Inactive RAM, the swapfile(s), or another file on the hard drive.
Pagouts occur anytime anything is moved out of Active RAM which includes mapping into Inactive RAM, as well as writing to a Swapfile. Only data is ever written to the hard drive since instructions are already on the hard drive.
If page-outs exceed page-ins, you definitely don't have enough RAM. Ideally, page-outs should be less than 20% of the number of page-ins (the fewer page-outs, the faster your machine is performing)
So you are perfectly fine with your 3 GB
To Tenfourfox which is esentially firefox , firefox has the habit of not empty its cache after you closed a tab instead keeps the info in its cache which is loaded in the ram for future use , say for example if you visit a site more often that comes handy as the site loads quicker .if you vist many sites tenfourfox is using more Ram to store all the date of one session
But i find Safari is even worse when it comes to ram usage .
Easy solution for that is eiter to close Tenfourfox from time to time or to empty the cache manually from time to time
On top of that all the plugins use ram too , not a lot but if you got many plugins it adds up as if they are enabled they all get loaded in the ram by tenfourfox , but unless you collect plugins for a hobby and have hundreds of them , but normaly the essential plugins will only be a couple mb in size all together
