[alcuadrado]

The performance seriously decreases. I haven't measure how much, but I guess it'd only work for very very small scripts.

[SaturateDK]

http://jsperf.com/jsfuck-test

[xxs]

once the eval() invocation is complete and the code generated/compiled the performance should be the same as the code normally written. Basically it's only compiler from []{}!+ to javascript.

[calibwam]

However, your js files would get really big, and download latency could actually be a performance drop.

[xxs]

True, however they should be very well compressible by 'deflate' too, the main concern is the initial parsing grok by the JIT. Yet, on runtime the scripts will be good as any.