9.1.4 Compression of CLOS metaobjects

To reduce the size of the delivered image, the delivery process compresses the representation of CLOS metaobjects (classes, generic functions and methods). This includes:

1. nullifying the class direct slots of the class.
2. Changing the effective slots to a function that is used in the initialization of the instance. This is controlled by :metaclasses-to-keep-effective-slots and :classes-to-keep-effective-slots .
3. Compressing the representation of method objects. This is controlled by : keep-clos . If :keep-clos is t , the representation of method objects is not compressed. There is also no compression if you add a method to method-qualifiers , method-specializers or method-function .
4. Compressing the representation of generic functions. This is not done if :keep-clos is t , or if you add methods to any of the accessors of generic functions.

LispWorks Delivery User Guide - 13 Dec 2011