Question: Is it worth to spend money on a small capacity HDD (~5-20 GB, very cheap though) to use it as swapping area for the OS? I do believe it will increase the OS performance , or maybe SSD (still ~5-20 GB), that costs more, will give better performances?
Answer: The best performance you get if you prevent from swapping in the first place – by having enough RAM (and upgrading RAM could be also the cheapest way).But if more RAM is not an option and your PC swaps a lot then new HDD or SSD will make things much faster. Also you should use all available physical drives for swapping (in windows), it should use them simultaneously so it will go even faster.And one more thing, HDD reads and writes faster on it’s beginning (when heads are near to edge of platter) so you should choose appropriate partition (usually the first one).