When I opened the creative inventory screen (potions), my fps dropped from about 25 fps to 8 fps.
When looking in the sky, my fps was 61 dropped to about 9
Environment
Mac OS X 10.9.3
MacBook White mid-2010 (RAM upgrade to 8 GB)
Java Version 7 Update 60 (build 1.7.0_60-b19)
Linked issues
is duplicated by 7
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I've experienced this as well!