What are the records for highest 1 year span performance rating? I've heard that Bobby Fischer had a 2892 performance in 1971. If this is true, it's probably the highest performance, but I don't know if this is true. Does anyone have any information about this?
Given Carlsen's 2882 current rating and the fact that he also reached this rating in 2014, it seems likely that at some point he had a year with a performance rating higher than your 2892 figure. (I calculated Carlsen's 2013 performance rating as 2890 [47 points in 69 games against an average opponent of 2757] but it's tedious enough to calculate that I don't want to do it for every year.)

However, if you use current FIDE rules on how to calculate performance rating, Fischer's performance rating in 1971 was even higher than the number you specified.

In 1971, Fischer participated in three official matches that I know of:

Fischer - Taimanov Candidates Quarterfinal
Fischer - Larsen Candidates Semifinal
Fischer - Petrosian Candidates Final  

(He also played some blitz and simul games, but I assume those don't count.)

Taimanov was rated 2620, Larsen was rated 2660, and Petrosian was rated 2640 at the times of the matches. Fischer scored 6/6 in the first two matches and 6.5/9 in the third, for a total of 18.5/21 and an average opponent rating of 2640.

18.5/21 corresponds to a fractional score of 0.88. According to FIDE regulations, this in turn means that the performance rating is 336 points higher than the opponent's average rating. 2640 + 336 = 2976 performance rating.

It's hard to say whether that's the highest ever, but it very well might not be, even setting aside powerhouses like Carlsen. Since a 100% score results in a performance rating 800 points above the average opponent, anyone whose record for a particular year consisted solely of a 100% match score against a 2200 player would have a performance rating of 3000. I'm guessing that has happened to someone at least once.