Eclipse hang when copying / pasting code
I solved this issue with these steps:
Identify which "editor" is causing the problem. I detected that, in my case, the java script editor was the one causing it, but when copy/pasting in a simple text editor, (no high light, no color , no nothing) there was no such problem.
Note:Eclipse loads the file in different "editor windows/ plugins" depending on the file extension, this is configured in General > Editors > File Associations
As my case was caused by the JavaScript editor, went to Preferences > Java Script > Editor > Typing, and disabled all the "Automatically" boxes. This made the trick.
I solved unchecking all bound to CTRL + C except Copy in Window -> Preferences -> General -> Keys
Disabling Hyperlinking fixed this for me. You could also just change the Default modifier key to something other than CTRL if you still want to use hyperlinking.
Go to Window -> Preferences -> General -> Editors -> Text Editors -> Hyperlinking and either uncheck Enable on demand hyperlink style navigation or change Default modifier key.
I had the same issue, and was able to solve it by going to: Preferences -> Javascript -> Editor -> Typing -> "When pasting" heading ... then turning "Update imports" off.
That one change on its own completely eliminated it, when I was previously getting hangs of 2 seconds or more on almost every copy or paste.