Probably unintentional leaking of optimization changes
f2cl/src/f2cl2.l#L16 The eval-when when includes load evaluates the form at load time, which in this case means doing the call ** (proclaim '(optimize (speed 3) (safety 1)))** at load time. That is a bad idea, because it means that after loading this fiile, anything that doesn't explicitly sets the optimize safety and speed level will be compiled with these setting rather than the default settings.
The other sub-form in the same eval-when form, the call to optimize with special, should happen at load time. So the right fix is to split these to two forms:
(eval-when (compile) (proclaim '(optimize (speed 3) (safety 1))))
(eval-when (compile load eval)
(proclaim '(special *intrinsic-function-names* *external-function-names*
*subprog_name* *subprog-stmt-fns*
*functions-used*)))