I have been using a Sony VAIO notebook computer with Windows-XP for a couple of years. This has been my primary "home-PC" which I used for things like managing finances, preparing taxes, wordprocessing, video- and photo-editing, and playing with software such as home-design, etc. I have also been doing a bit of Perl and C++ programming, besides tinkering with MySQL, PHP and Drupal.

All this was running on a mere 512Mb RAM that came with the PC!

The PC was sometimes getting a bit sluggish especially when I had multiple copies of browsers running. And I have been thinking of adding some memory.

Over the last weekend, I upgraded the memory to 1GB (the maximum allowed by the design). And within moments, I could see the difference.

Doubling the memory on-board has more than doubled the productivity of this computer. It clearly shows that memory was the primary bottleneck until now. I can see a dramatic reduction in pagefile swaps. Almost any application that I click on comes up instantly.

But this is also a case of diminishing returns. If it were possible to go from 1GB to 2GB on this PC and if I did it, I am fairly certain that I would not get another two-fold increase in performance. That is because, the new bottleneck is probably the CPU flops, or bus-speed, or disk-access speed, or even the bulky Windows OS.