You can specify the types of optimized code to be generated by using the /tune option. Tuning for a specific implementation can improve run-time performance; it is also possible that code tuned for a specific target may run slower on another target.
On ia32 systems, regardless of the specified keyword for /tune, the generated code will run correctly on all implementations of the ia32 architecture. Specifying the correct keyword for /tune for the target ia32 processor generation type usually slightly improves run-time performance.
The /tune keywords are described in /tune.
The combination of the specified keyword for /tune and the type of processor generation used has no effect on producing the expected correct program results. To request a specific set of instructions for an ia32 architecture generation, see the /architecture option.