When I have to use information and performance I'm always confused.
However, I'm asking whether when I'm referring to more than one piece of information of performance I should use "information/performance is" or "information/performance are."
First, "information" is always written "information". Even when referring to more than one datum.
Secondly, "performance/Performances" is used based on the context. When referring to separate events, then "performances" is used. However, if referring to the same event "performance" is used:
Although the "performance" in the first test might refer to several different actions such as running, jumping, swimming, etc. (depends what the test is), because it still refers to one event taking place, one entity occurring, "performance" is used.
Not until, there are two separate things happening, is "performances" used.
Also note, in both cases, "information" not "informations" is used. that's because "informations" is wrong. It can only be used in certain places, as most instances of "information" are uncountable. In the legal sense, however, "informations" is used.
In American English, you always use is with information and performance, even if you are referring to more than one piece of information or more than one performance. You may be being confused by data, which can be both a singular or a plural noun; but there are very few nouns like that in American English.
Information is an uncountable noun, like water. You don't say an information or informations. You say
if you want to specify that there is only one.
Performance, if you are talking about the performance of a piece of software, is also uncountable. To make it singular, I would use a phrase like
If you are talking about theatre, it's countable: "I went to a performance of Hamlet yesterday."