After updating Fiji today, it became terribly slow when using the Channes tool. Up to the point where it would freeze entirely. 
Having done a lot of back and forth and updating my (Oracle) Java to 1.8.0_51, I could still not fix the problem. Therefore, I downgraded to the current Life-Line version from Nov 25, 2014 and everything was working again. 
I then upgraded all components step by step and found that updating "Contents/MacOS/ImageJ-macosx" (released Jul 15, 2015) causes all the trouble. Without this update, Fiji is running Java 1.6.0_65 according to the status bar (despite 1.8.0_51 still being installed and also being shown in Terminal when using the "java -version" command). After updating "Contents/MacOS/ImageJ-macosx", the status bar shows Java 1.8.0_51, but Fiji exhibits the deficits mentioned above.

If you need any further information, please let me know.

Glad for any help on this issue (although for now I found a way to work again).

Best,
Jan.

Information about your version of Java:

  os.arch => x86_64
  os.name => Mac OS X
  os.version => 10.10.4
  java.version => 1.6.0_65
  java.vendor => Apple Inc.
  java.runtime.name => Java(TM) SE Runtime Environment
  java.runtime.version => 1.6.0_65-b14-466.1-11M4716
  java.vm.name => Java HotSpot(TM) 64-Bit Server VM
  java.vm.version => 20.65-b04-466.1
  java.vm.vendor => Apple Inc.
  java.vm.info => mixed mode
  java.awt.graphicsenv => apple.awt.CGraphicsEnvironment
  java.specification.name => Java Platform API Specification
  java.specification.version => 1.6
  sun.cpu.endian => little
  sun.desktop => null
  file.separator => /

The up-to-date check says: REMIND_LATER

Information relevant to JAVA_HOME related problems:

  JAVA_HOME is set to: null
  imagej.dir => /Users/jan/Desktop/Fiji.app

Information about the version of each plugin:

Activated update sites:
ImageJ: http://update.imagej.net/ (last check:20150715230840)
Fiji: http://fiji.sc/update/ (last check:20150714182641)

Files not up-to-date:
  f5931f21 (UPDATEABLE) 20141119223236 Contents/MacOS/ImageJ-macosx
  1ad3be0d (LOCAL_ONLY) 20141119223240 jars/jpedalSTD.jar