URLs without Trailing Slash - Kill Performance - ~5 sec per page load - htaccess help?

Did you know the absence of a trailing slash costs about 5 seconds on page load time?
Well neither did I.... I'm running multi-site with child blogs. Links without the trailing slash take about 5 seconds extra to load from the redirect.

I can't seem to get any .htaccess fixes to work except for a simple redirect. This one works fine:
Redirect 301 /foobar /blog/pemf/

But more complex rules don't:
Here are two I've tried. Here is an article on the topic.

# Doesn't seem to work (preferred)
RewriteEngine On
RewriteBase /
RewriteRule ^([a-zA-Z0-9]+)/$ /$1 [L]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([a-zA-Z0-9]+)
RewriteRule ^([a-zA-Z0-9]+)$ /%1/? [R=301,L]

# And niether does this one
# If requested resource does not exist as a file
RewriteCond %{REQUEST_FILENAME} !-f
# and does not end with a period followed by a filetype
RewriteCond %{REQUEST_URI} !\..+$
# and does not end with a slash
RewriteCond %{REQUEST_URI} !/$
# then add a trailing slash and redirect
# This one can't work because I have other subdomain sites running too (just a test though)
RewriteRule (.*) http://whnlive.com/$1/ [R=301,L]