Any time where you can let you computer get what it needs from RAM instead of the hard drive it will take less time. This may be through giving an application more memory , increasing your disk cache , or turning off virtual memory . When I get a phone call with someone asking about upgrading the memory in their Mac the first thing I do is launch a little application called Guru from Newer Technology . Guru tells me all the information I need to know about how much memory their machine came with and how much it can take. Guru also can help you plan out what memory goes in which slots by clicking on the 'Configure Memory' button.
RAM comes in different shapes, sizes, and speeds.
The kind of RAM you need depends on your machine. Each kind of RAM can only fit in its kind of slot. Your computer can deal with a certain size chunk of data at once. This is why DIMMs can be installed one at a time. But Apple didn't stop there.