Generally, more cache means better performance, and 256K or 512K Level 2s are typical of the highest-priced PC chips. Caches inside the chip itself can also improve performance. With the advent of multimedia PCs and the Web, CPU vendors have dedicated special logic circuits, or instructions, to the complex calculations required to process large graphics files and videos. Intel was the first to do it with its 57 MMX instructions added to the Pentium in early 1997. PC makers, however, are starting to use the instructions for software-only DVD decoding and for modems.
System buses are also key performance factors.
But both will remain underused until a new generation of faster memory arrives next year. Independent benchmark tests designed to compare performance generally show AMD chips matching that of equivalent Intel products. Chips from Cyrix, IDT and Rise Technology also typically match the overall performance of their Intel equivalents, especially in graphics. But delays in technical innovation and obstacles to mass production have prevented rival companies from keeping pace with Intel as the processor giant introduces next-generation chips that provide superior performance for the same money. Some benchmark tests attempt to isolate the CPU and its supporting subsystem.