Computers process millions of bits per second and this number doubled every 18 months. The problem is that the amount of information doubles every year while computer power takes 50% more time to double its power to process that information.
There comes a time when the computer becomes so slow that it takes several seconds to respond and even more to execute your orders.
1. Add more RAM. Computers which run out of RAM simply work more slowly and crash more often. Even though Windows 7 never crashes, or at least never crashed with me for over a year, without enough RAM the computer becomes as much as 100x slower. If you cannot afford more RAM, remove some software, disable the virtual memory and use Mem Cleaner to free RAM every 15 minutes.
2. Add an SSD hard disk. The regular hard disks are too slow, crash if the computer falls down, are used as virtual RAM and make the computer ten times slower and can crash anytime without warning. SSD hard disks are very expensive and have just a few GB of capacity but if you need to work with large amounts of information quickly they are for you.
3. Move all your information and software to the cloud. Gmail is the fastest email platform, not even Outlook 2010 in the fastest computer beats Gmail. The same is true for documents, images, video, etc. The cloud is faster than the computer and moving files to the cloud makes the computer faster because the computer will be free of too much information inside it.