Memory leak is not a very nice sounding thing, and it is an issue that is as bad as it sounds. It is though a lot different than it sounds as memory leak would make sense that the memory slowly gets used up as opposed to lost right away. When the memory does get used up it is leaked away from the actual ability to use it, but does not get lost forever. Memory leak usually refers to a program that continues to consume the memory of an operating system after it is generally designed to do so. This can often happen in older operating systems as the amount of actual memory is not a lot so the leak or continued retention of the memory can be seen a lot in the performance loss.
The best way to explain memory is with an example. If there was a vending machine that had directions as follows:
1. Count money inserted.
2. Total money.
3. Take selection input
4. Validate selection, if invalid then advise of alternate choice.
5. Accept correct selection.
6. Deliver product.
If there was 100MB of memory to start with and someone got to the 4th direction and continued to choose incorrectly and the system was not designed to release the memory after the alternate selection was chosen then it could possibly hold onto that memory forever. Although it might not slow down right away if there were 1000 people that all made the wrong decision over and over it would eventually slow down the system, and could possibly cause it to crash. Resetting the system or program are usually the only ways to restore the memory lost in leaks. Usually memory leaks are not seen right away but as this example showed it would not be good to be the victim of memory leak if you were the 1001 person who wanted a chocolate bar from that vending machine.
If your computer system is starting to slow issues with performance and is slowing down it could be caused by memory leak or by a lot of different issues. If this is the case and you want your computer to go as fast as it first did then the best thing to try is a registry cleaner. A registry cleaner will look for any issues within the registry of the operating system being used and can help to identify ways to get the lost memory and speed back onto the system. Memory leak is an issue that is no good to be encountered so it is best to ensure that all updates are current on the system that is being used as well as a clean registry.