What is performance?

[tOmcOlins]

I'm sorry, I check the news and browsed the forums, but I could not find anything explaining what "performance" is. My performance bar is "n/a", I thought because I haven't done 100 problems yet, but I see that there are many other people who have solved less than 100 and even people who have solved fewer than I have, and have performance bars.
Can someone please explain or point me to an explanation of what performance is actually a measure of?

Thank you

[JohnMorris]

It is proportional to many of the most recent 25 problems you have solved - currently that would be numbers 178 though 202.

(The ranking system is being re-vamped just now. Take a look at the "New Ranking System (Feedback)" thread in this forum for the discussion. Once it is finished I am sure this will be all well documented on the problem pages.)

[Georg]

It is the number of solved problems from the last 100 problems (103 to 202) / 100.

[euler]

Sorry, it have accidentally become the last 100 in the process of removing the "ranking" system and it should have been the last 25 problems; I've just changed it back. As Thumbo explained, a fully explanation of all the up-coming changes will be given once the details have been finalised.