1. Almost every new Windows computer will ship with unwanted software. These programs subsidize the cost of Windows home edition coming pre-installed, which would normally cost over $100 purchased separately. The most effective solution is to reinstall the operating system from the disk. In fact, it is good practice to reinstall your operating system every few years anyway. If you really want to avoid a clean install, you can run the PC Decrapifier, which allows you to bulk uninstall the crap.
2. You need to tame your virus scanner. Virus scanners, yes the programs you use to scan and remove viruses, are notoriously bulky and have no sense of boundaries. They tend to run in the background at all times sucking up resources. would just install Microsoft Security Essentials and uninstall the rest.
3. Scan and remove Malware. Microsoft Security Essentials is great, but it does miss some things, so if you have a serious malware problem, get Malware Bytes. It blows all the other scanners out of the water.
4. Uninstall unused programs, the right way. Unused programs don’t necessarily slow down your computer if they never run, but a lot of them have hidden auto-running elements. Also, the more programs you have installed, the more expensive your registry becomes, so anything that reads from your entire registry is going to be throttled. Get Revo Uninstaller and it will uninstall the features that the stock Windows uninstaller leaves behind.
5. Upgrade to maximum memory. Memory is usually the cheapest and easiest hardware upgrade you can perform for both laptops and desktops. Go toand you can find out where your computer maxes out on memory and upgrade. The days, you should not have less than 2 GB of memory. Bear in mind that to go much above this you will need a 64-bit operating system or you computer won’t be unable to use all the extra memory you install. That means you also need to be sure that your processor can handle 64-bit instructions. Google around a bit to see if your computer is capable of a 64-bit operating system.
6. More significant hardware upgrades: a multi-core processor, a newer model video card, and a solid state hard drive will probably be the next step in improving your computer’s performance, but these are much more costly. You should seriously consider at this point whether it would be better to sell your computer on eBay, Craigslist, or Amazon, and just get a whole new computer.
Source : quora