program optimisation vs British spelling

program optimisation and British spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
program optimisation	Yes	No	No	No
British spelling	Yes	No	No	No

program optimisation (noun)	British spelling (noun)
the process of modifying a software system to make some aspect of it work more efficiently or use fewer resources.	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')