While reading the source, I noticed in bytecode.c that:

    /* Inline the most common case.  */
    if (SYMBOLP (sym)
&& !EQ (val, Qunbound)
&& *!XSYMBOL (sym)->u.s.redirect*
&& !SYMBOL_TRAPPED_WRITE_P (sym))
      SET_SYMBOL_VAL (XSYMBOL (sym), val);

should be:

    /* Inline the most common case.  */
    if (SYMBOLP (sym)
&& !EQ (val, Qunbound)
&& *XSYMBOL (sym)->u.s.redirect == SYMBOL_PLAINVAL*
&& !SYMBOL_TRAPPED_WRITE_P (sym))
      SET_SYMBOL_VAL (XSYMBOL (sym), val);

As it is, the inline case is never run, since "redirect" is always non-zero.

Since I'm new to emacs internals, I don't know how to benchmark to work out
if this makes a noticable performance difference. :)

Thanks,
Simon.