Data Flow  The processing speed of a computer system depends on how fast the data is fed to the CPU and the actual processing speed of the CPU itself. Integrating the latest storage technology into your system and optimizing it for the maximum performance requires an understanding of the system's architecture and peripherals specifications to achieve maximum data I/O speed. This requires carefully choosing the right hardware and connectivity products tailored for your specific application and budget
Storage  Ultra SCSI or Ultra 2 SCSI can be connected internally to save external enclosure cost, ideally there should be no other device connected to the SCSI chain, if any slower SCSI drive is connected, like Zip, Jaz or DAT the whole SCSI chain will operate at that speed (i.e. Xfer Rate reduces to 5-10 MB/s). .
Connectivity High Performance external disk drives or disk arrays connected using PCI SCSI cards offers substantial increase in data transfer rate compared to connecting them with systems on board SCSI ports. The difference of performance advantage is 70 MB/s (theoretically)
Processor The CPU is where all information is processed, the clock speed, size of the cache buffer and speed of the cache of the CPU is critical for data processing at high speed. New faster CPU upgrades are available as the technology moves on. CPU upgrades provides another inexpensive solution to add performance to the computer , considering the cost of a new computer.
Memory  The main memory in the system acts like a cache buffer between the system's CPU and disk drive. System performance depends on two important factors. 1) How fast the data is brought from the disk drive to the RAM (main memory) of the computer. 2) How much data the system's RAM can hold? Factor one is dependent on the connectivity of the drive in the system. Macintosh internal or external ports do not allow more than 5-10 MB/s. Higher speeds up to 80 MB/s are possible by integrating an Ultra 2 SCSI PCI card with an Ultra 2 SCSI drive
Data Access Factor two is the key to higher performance. More memory enables more data to be accessed at higher speeds. The transfer rate from RAM to the CPU is a million times faster than the transfer rate between the disk drive and the CPU. For example: The difference between data accessed from PC-100 SDRAM operating at 8 nanoseconds, when compared to 7200 RPM, 8 millisecond SCSI hard drive will be exactly a million times faster than the SCSI disk drive. Note: One millisecond is equal to 1/1000 (One thousandth of a second) One nanosecond is equal to one 1/1000000000 (One billionth of a second) The difference between data accessed from RAM and the disk drive is (1/1000000) (One millionth of a second).   Therefore, maximizing RAM is the most inexpensive performance upgrade possible.