lots of redirects in htaccess

Giganews Newsgroups
Subject: lots of redirects in htaccess
Posted by:  der…@stonebrookdesigns.com
Date: Thu, 23 Jul 2009

I have more than a thousand distinct sites under a single domain
name.  For now, I want their addresses to be something like, www.domain.com/site1
and www.domain.com/site2

However, rather than having 1000 directories in the home directory,
for asthetic purposes, I would rather put them in a sub-folder like

But for ease of users typing the address, I want the www.domain.com/site1
to redirect to the subfolder.  Is the best way to do this by
redirecting them all in the htaccess file?  I have heard that too many
entries can slow down the site.

If htaccess isn't the way to go.  What would be the best?