<b>Cache memory</b> is random access memory (RAM ) that a computer microprocessor can access more quickly than it can access regular RAM. As the microprocessor processes data, it looks first in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the more time-consuming reading of data from larger memory .
<b>Hard disk cache</b> will hold files in memory that are used quite often or for prefetching. Memory transfers will always be faster than reading off hard drives. So the more cache you have the more files can be held in memory, the faster the drive will be for those files. Once it has to pull off the hard drive you’re back to normal speeds.
<b>L2 cache memory</b> is on a separate chip (possibly on an expansion card) that can be accessed more quickly than the larger “main” memory. A popular L2 cache memory size is 1,024 kilobytes (one megabyte).