fast processing in brain

You must have heard people saying that "do not indulge in useless things". Why, let us take the example of computer. Like humans, computers also have memory to store data and processor to process the data. Now, the data which is required very frequently is stored in processor registers. Now to produce right results it is very important to have the right data(always applicable in case of computers) in memory. If wrong data or extra data keep residing in the processor memory then either the result will be wrong or delayed.
Similarly, human brain also processes the data which is available to it. Now, how the data is made available to the brain, through our memory. And, what is contained in our memory, the
thoughts generated by the activities in which we are involved. Now, if we keep ourselves involved in useless things then this data always keeps the active memory(let us call processor registers as active memory to talk about human brain) full and when we need to think on something else or something useful then it will take time to make it available to the brain as some other data is already there in active memory.
For example, if you are crossing a busy road with a contained mind then you will take more time to react against a fast coming vehicle. What can be done to avoid this, to keep the active memory free and to process the data fast. Now, after realizing the logical reason behind the processing of data in your brain and understanding how useless indulgence can be responsible for making you slow. Then, any time any place you can give a thought to know your state of mind and you will come to know that what is there in your mind, is this really useful, necessary. Slowly slowly you may start checking your memory very frequently and help yourself in keep it clean from useless data(thoughts).