This is a technique I would only recomend to someone that understands how thier specific compiler actualy works, and the optimizations it performs itself. Some compilers, (Cobol 2 >, HLASM, etc...) already perfrom this one automatically so there is no need with them, some, like C# do not.

This optimization, also goes against code re-usuablility/maintainablilty priciples, and should only be considered where performance is a must need, and usualy best to contain it to a one time/or limited usage type situation.

Mainly it involves going through your code, and removeing all function/method calls, and copying that code back to where it's used, inline.

It's usefulness is limited to fucntions/methods that are in often repeated loops or code.

This will not effect huge gains, but it will eliminate 2 to 4 instructions per function/method call transitioned to inline, (eliminates a branch and return, and the instuctions involved in passing and returning paramaters).

In some large loops this might be a benefit. But again, it's a very specific optimization that I would not normal recomend in day to day coding. However for HPC it might be something to consider if maintainablitiy is not as much of an issue as speed of operation.