Affects Version/s: Minecraft 1.5.1
Fix Version/s: None
Environment:i7-3970X - 4.4GHz (OC) 12 threads, 6 cores on water cooling
GTX 690 (Two 27in 1920x1080 monitors)
64GB DDR3 1333MHz
4x 128GB SSDs in RAID 0 (2,300MB/s R/W)
Java 1.7 (latest revision)
Title about sums it up, brand new Minecraft world, I give it a few minutes to let the chunks load, and standing perfectly still I fluctuate from 40 to 70 FPS... this certainly should not be the case.
Installing optifine gives me about 7 FPS increase at best.