Russell Whitaker wrote:

the difference is insignificant

for a loop of 1 billion times: 2.421 vs 2.412 sec.

More clearly, the generated code is exactly the same. You can compare the generated assembler, object or executable files, and will find no difference (except perhaps a timestamp in the header which you'll also find when compiling the same program twice).

Any decent compiler in the last few decades has done this, so it's really a no issue today.

The real differences are that OTH "x := x + 1" is standard, while Inc is UCSD Pascal, OTOH when the object is a complex expression (e.g. "Inc (MyArray[ ... longish expression ...])", Inc makes for shorter code, both on the source level and (depending on the complexity of the expression and compiler optimization) possibly also in generated code and performance.

Frank