Ok, Firstly when you want to look at memory usage, do it while in game, if you are using 16% memory, the game is certainly not running.
There is always 2 processes of swtor.exe one will be the main game the other I am unsure, but this interprocess communication I feel is a reason for some of the lag we see. But this is another side point.
This game is a 32bit game, therefore installing more than 4GB of RAM and running a 64bit OS is not the solution. There is some issues though I have seen with 32bit applications running and needing more RAM that what Windows will allow.
32bit application are allowed to utilise 2GB of RAM in Windows. This can be an issue, especially when games like SWTOR certainly need more. BUT. There is a thing called PAE, which is Physical Address Extensions when enables 36bit addressing when then enables the use of about 3GB of RAM per application. To check to see if PAE is on. It says that it is on by default if the machine support hardware DEP. But this is different for each machine and I have needed to turn it on sometimes.
For Information of PAE and updating.
My suggestion is to try this even if you feel it is already on, give it a try. Another, due to the massive memory contingent required for SWTOR, check the size, location of your swap file. If you open Task Manager and on the processes tab you can view the number of Page Faults (this often needs to be added), if SWTOR.exe is performing a lot of Page Faults, it means it is accessing the Page File a lot. Try increasing the size of the file or
check the disk the page file is on. The page file might have some bad sectors on the disk. So perform a chkdsk If it is happening at regular intervals then it seems that there are issues with your system and it causing it to crash.
Also, try PageDefrage
. This is an advanced topic and is only recommended if you know what you are doing. Defrag the drive that the page file is on, this will help create more contiguous spcace. Then run the PageDefrag. Next reboot it will perform this task. NOTE. Read the page carefully and do not assume anything. The Defrag the Page file is OK, but leave the registry hive alone.
I am not sure what else could be offered. Yes upgrading to 64bit OS will remove a lot of memory constraints, evening on a 4GB system this can help give you a little more memory but it will also mean 32 bit applications can access all of the 3GB possible for a 32bit application.
So before you run, check the amount of free memory available on your system as well. Make sure it is enough, stopping processes not needed can help. Stopping services that aren't needed helps more. Other than those thigns I am not sure where else to go, as I am also unsure what else BioWare could do as well, since this is sounding like a specifc problem.
Also if you could post the specs of your machine. Provide information from the eventlog or the reliability history, since the module that it fails in might help with finding the solution.