Redo performance plots with correct multiprogrammed results.

PERFORMANCE.md

@@ -50,7 +50,9 @@ Currently the FFT benchmark shows the following results (average):
 We want to positively note that the overall trend of 'performance drops'
 at the hyperthreading mark is not really bad anymore, it rather
 seems similar to EMBB now (with backoff + lockfree deque + top level
-reader-writers lock).
+reader-writers lock). This comes partly because the spike at 4 threads
+is lower (less performance at 4 threads). We also see better times
+on the multiprogramed system with the lock-free deque.
 
 This is discouraging after many tests. To see where the overhead lies
 we also implemented the unbalanced tree search benchmark,