You might well find that increasing your RAM (memory) to 4GB will improve your memory usage AND reduce the load on the CPU as well. This is because the CPU is also acting as the memory controller, and a low amount of memory means more work for the controller, plus the data busses on your system are constantly being used to transfer data between the paging (swap) file on your HDD and the RAM instead of carrying data pertinent to the application (which has to wait until there is space in the RAM for it). Whilst increasing the amount of RAM will not eliminate this type of data transfer altogether, it can help to reduce the amount and frequency that needs to be transferred. As a result, your system should feel more responsive.
Unfortunately, apart from the low RAM amount, you haven't given us much to go on. Referring to your image of Windows Task Manager (WTM), this might give us a clue as to where the potential problem could lie. Open WTM again, click on Show processes from all users (provide administrative credentials if/when prompted) and then click CPU to sort the results so that the processes which are taking the most CPU time are at the top. Repost the image showing the results.