There's also the cacheing of the compiled bytecode of *.tcl pages
beneath the www/ pageroot using ns_cache, which Rob Mayoff implemented
in
aolserver/tcl/file.tcl
and
aolserver/tcl/tclcache.tcl
in 3.3+ad13. That's not in
4.0 yet either.
However, that's a performance issue only, everything will work without
it, and it would probably only be important for high volume sites.
(So far, no one as really characterized the performance difference.)