On RISC computers there are no microprograms. Machine instructions are implemented directly in hardware. Any task too complex for the hardware to execute in a single cycle is done by executing a series of basic instructions, either as in-line code or by calling a subroutine.
Extensive research into patterns of computer usage reveals that general-purpose computers spend up to 80% of their time executing simple instructions such as load, store, and branch. The more complex instructions are used infrequently. On architectures with large, complex instruction sets, the simple, often executed instructions incur a performance penalty by the overhead of additional instruction decoding, the use of microcode, and the longer cycle time resulting from increased functionality.-----Hewlett-Packard's "Precision Architecture and Instruction Reference" manual.