Complex sentence: Initially Cyrix tried to charge a premium for its extra performance, but the 6x86's math coprocessor was not as fast as that in the Intel Pentium, the main difference being not one of actual computing performance on the coprocessor, but the lack of instruction pipelining.
Split into simpler sentences: Initially Cyrix tried to charge a premium for its extra performance, but the 6x86's math coprocessor was not as fast as that in the Intel Pentium. The main difference was not one of actual computing performance on the coprocessor, but a lack of instruction pipelining.