I should had said that it happened with a diamond sword.
These are all the reports of the cutting grass crash.
It happened with a World created with the 14w26b version. Now I create a new World with the 14w26c version and that doesn't happen.
It happened with a World created with the 14w26b version. Now I create a new World with the 14w26c version and that doesn't happen.
But on 1.7.10 I don't have that problem. Only on the beta version.
I have around 10-15 fps less with VBO on.