Enable computed gotos in the VM on compilers that support it

[Gundolf68]

This gives a noticeable performance boost.

[ThakeeNathees]

Yeah, It's a great idea, That'll boost the performance a considerable amount. Thanks for the suggestion, I'll add this to my TODOs.

(Note for anyone willing to open a PR: First of all thanks but, because this is an architectural change, open an issue discussing the implementation first)