Package caching

I ran the Cywgin `xemacs'; I notice it's quite fast once it starts up but dog-slow doing so. I imagine much of the time is spent doing multiple stats down through the package tree. I'd like to suggest the following: The basic idea is that upon first startup XEmacs remembers the package roots and the contents and modification dates of all the directories it has to traverse. Ideally this remembrance should be done in some system-wide place but this may not be possible unless xemacs is running as `root' -- therefore, either we do this automatically when xemacs is run this way, or we just do it using a flag, which can function as a way of a sysadmin updating the cache. In other circumstances, use a file in ~/.xemacs. Then, next time, use this cache instead of actually reading the directories. However, go through each resulting directory in load-path and stat it to see what the modification time is; if so, we need to discard the file listing for that directory and reread it (thereby potentially adding new directories to the cache that need to be recursed into, or removing directory trees from the cache). As far as I know, this algorithm/procedure has many advantages: [a] simple [b] 100% accurate [c] relatively fast -- it requires that we stat only once per directory instead of once per directory entry, plus three times extra per directory (for default, default.el, default.elc), plus probably other overhead. [d] allows but does not require the administrator to run a command to generate the cache