If you are feeling that your computer is running very slowly, you may want to try defragmenting your hard drive. If that does not resolve your problem, you may want to increase the computer's memory eg: from 4GB to 8GB or 16GB (only available for Quadcore CPUs. Please check the availability on the CPU manufacturer's website). The increase of memory or RAM (Random Access Memory) will append up temporary storage while the computer is switched on.
If that does not resolve the overall performance of your computer, you might need to change your graphics card (note: graphics card on a laptop is virtually non-replaceable unless it runs on Nvidia's MXM series).
Your next move should be looking at the performance of your computer's hard drive. This is truly important because the hard drive will store all of your data even if the computer is shut off so you need a fast and reliable hard drive without breaking your bank account to do so.
These days hard drive usually comes with either a solid state drive or a mechanical drive. If your computer comes with a mechanical drive, it will allow you to look at the rotation per minute ie: rpm. The theory is that the faster the platte inside the hard drive spins will ensure that data will be accessed much quicker. Usually you will see a typical desktop hard drive ie: 3.5" 7200rpm loaded with 32MB cache and a laptop hard drive may spin at 4200rpm loaded with 8MB cache.
However, one may find a better hard drive installed on their computer which will be great! These mechanical hard drives have one or two problems. Irate of all, they are noisy when the platte in the hard drive spins. If you have a hard drive which spins faster, it may create more noise in the end. With a fast spinning hard drive, it may cause the hard drive to produce more heat. This will be quite uncomfortable particularly if one is using a laptop on his/her lap.
There is an alternative to the mechanical drive which is solid state drive. There are many advantages in using a solid state drive as opposed to the disadvantages. First of all, all solid state drives use flash memory (just think of your USB flash drives) so it is really quiet. Apart from that, it does not produce as much heat as a mechanical hard drive because it does not have any moving parts. The only heat will be emitting will be from the NAND flash chips on the solid state hard drive itself.
Thirdly, it is lighter in weight as compared to a mechanical hard drive. This is quite important if you are thinking of shedding some weight in carrying your laptop around.
Above all, data access speed on the solid state drive is pretty quick. One good example is the 256GB Samsung 830 series solid state drive where the read speed is up to 500MB/s while the write speed is up to 400MB/s! This is much faster than a typical laptop hard drive (5200rpm; 8MB cache) which access data at a speed of 80MB/s in the real world!
However, a user will have to contemplate the disadvantages of buying a solid state drive. It is expensive to buy a solid state drive and it comes with a small capacity unlike the mechanical hard drive. Often than not, many power computer users will buy a solid state drive just to boot into the operating system (OS) while maintaining the mechanical hard drive for storage purposes. This idea prove to be quite popular.
In deciding which solid state drive to purchase, one would have to do some research. Often than not, one would have to read some reviews eg. PCworld, Techno Buffalo, Techradar and so on. Please try not to stick to one review but read as many reviews as you could before making a conclusion.
If you have decided to make a purchase for a specific solid state drive, you would have to do some research in getting the best price possible. One could achieve the purpose by searching online via eNay, Amazon and Bestbuy (In the UK it will be via carphonewarehouse.com).
Apart from that, don't just ignore small and independent online retailers. Personally, CCLonline and Lasky.com seems to be offering some good deals apart from ebuyer.com. The rule of thumb in buying anything online is that you will be protected under the Distance Selling Regulations throughout Europe.
Personally, it is submitted that the Samsung 830 series solid state drive is one of the best solid state drive in the market without breaking one's bank account. If one is interested in purchasing a 128GB version, the cheapest at this time of posting is Amazon UK (£77.99 including postage) while the 256GB version is being sold at £149.97 including postage. Please be aware that if one were to purchase from Amazon UK, the buyer will be entitled for free posting. Best of all, delivery will take place under three working days. I have similar good track record with other sellers which I have mentioned above.
At the end of the day, one should always do some research before making a decision to buy amy solid state drive. Given the price drop and the reliability of Samsung solid state drive as they use their own products to produce the solid state drive, the Samsung 830 series solid state drive is the most affordable in today's term when looking at the price/capacity/reliability/speed issue.
Apart from the Samsung 830 series SSD, one could also try PNY SSD series which has similar specifications as the Samsung 830 Series and it cost almost the same too.
Update II (13/02/2013):
You could pick up a 512GB Lite-On SSD from ebay or Amazon for around £220 in the UK. The performance of the Lite-On SSD is comparable to the Samsung 840 Pro without breaking anyone's bank account.