Fix wrong comment

This was already changed to 120FPS in
e0b49e7, but it looks like we forgot to
update the comment.

Author: vimpostor

tests/test_general.vim

@@ -121,7 +121,7 @@ func Test_performance()
 
 	exec printf("profile start %s", log_file)
 	profile func tpipeline#update
-	" simulate someone scrolling at 60FPS
+	" simulate someone scrolling at 120FPS
 	func Scroll()
 		if line(".") - 1
 			norm k