The speed of RAM is generally faster compared to ROM. This difference is primarily due to their respective technologies and roles in a computer system. RAM is designed to be rapidly written to and read from, facilitating quick access for the CPU to currently active data and applications. Its architecture, whether DRAM or SRAM, is optimised for speed to minimise latency during data access. In contrast, ROM is primarily intended for storing firmware or essential booting instructions, where speed is not as critical. The construction of ROM, being pre-programmed or not requiring frequent updates, does not necessitate the high-speed architecture of RAM. The speed of ROM is sufficient for its purposes — being read upon system boot or in specific operations where data permanence is more crucial than quick access.

Insufficient RAM in a computer system can lead to several noticeable performance issues. When the RAM is fully utilised and the system requires more memory to function, the operating system begins to use part of the hard drive or solid-state drive as a "swap space" or virtual memory. This swap space acts as an overflow for RAM, but it's significantly slower, leading to a noticeable decrease in system performance and responsiveness. Applications may load and respond more slowly, multitasking becomes less efficient, and the system might experience increased lag or "stuttering". This is particularly evident in resource-intensive tasks like gaming, video editing, or running multiple applications simultaneously. Moreover, excessive use of swap space can lead to increased wear and tear on hard drives, particularly SSDs, which have a limited write lifecycle.

A computer primarily uses ROM during the boot process and in scenarios where unchanging, essential instructions or data need to be reliably stored. ROM contains the firmware or BIOS (Basic Input/Output System), which includes the fundamental instructions that allow the computer to start up, perform self-checks, and initiate the loading of the operating system from secondary storage. Since ROM is non-volatile, it ensures that these crucial instructions are always available and uncorrupted, regardless of power state or system errors. This reliability is essential for system stability and integrity. Additionally, ROM finds applications in various embedded systems (like in microwaves, cars, or industrial machines) where a stable, permanent set of instructions is required for the device's fundamental operations, offering a high level of dependability for essential tasks.

Although ROM (Read-Only Memory) is primarily designed for permanent storage and typically comes pre-programmed from the factory, there are certain types of ROM that can be modified or updated under specific conditions. Programmable ROM (PROM) can be written once after manufacturing; once written, the data can't be erased or changed. Erasable Programmable ROM (EPROM) can be erased and reprogrammed, but this requires exposure to strong ultraviolet light, after which it can be reprogrammed using a special device. Electrically Erasable Programmable ROM (EEPROM) allows for data to be erased and reprogrammed electrically, making it more versatile for tasks that require regular but infrequent updates, like firmware updates in various electronic devices. The ability to update these types of ROM enables firmware revisions and functionality upgrades in hardware without needing to replace physical components.

Primary memory, especially RAM, is considered volatile because it loses its stored data when the power supply is interrupted or turned off. This characteristic has significant implications for data storage and processing in computers. Since any information stored in RAM is lost upon power loss, it's not suitable for long-term data storage, which is instead handled by non-volatile memory like hard drives or SSDs. The volatility of primary memory is beneficial for temporary data storage and quick access, allowing the CPU to rapidly retrieve and process data that's actively being used. This leads to quicker data processing and ensures that sensitive data is not left stored in memory after power off, which can be a security measure. However, it also means that unsaved work can be lost in cases of unexpected power outages, underscoring the importance of regularly saving data in non-volatile storage.