Suggestion on .htaccess

This is a .htaccess for a MU blog the index file is kept at : public_html/ And main blog is kept at: public_html/blog It is causing severe cache issue. SuperCache plugin is not working. The blog is running out of memory most of times and consuming huge CPU. Any suggestions? # BEGIN WPSuperCache <IfModule mod_rewrite.c> RewriteEngine On RewriteBase /blog/ AddDefaultCharset UTF-8 RewriteRule ^(.*) /blog/wp-content/cache/%{HTTP_HOST}/blog/$1/index.html.gz [L] RewriteCond %{REQUEST_URI} !^.*[^/]$ RewriteCond %{REQUEST_URI} !^.*//.*$ RewriteCond %{REQUEST_METHOD} !=POST RewriteCond %{QUERY_STRING} !.*=.* RewriteCond %{HTTP:Cookie} !^.*(comment_author_|wordpress|wp-postpass_).*$ RewriteCond %{HTTP:Accept-Encoding} gzip RewriteCond %{DOCUMENT_ROOT}/blog/wp-content/cache/%{HTTP_HOST}/blog/$1/index.html.gz -f </IfModule> # END WPSuperCache #uploaded files RewriteRule ^(.*/)?files/$ index.php [L] RewriteRule ^(.*/)?files/(.*) wp-content/blogs.php?file=$2 [L] RewriteCond %{REQUEST_URI} !.*wp-content/plugins.* # add a trailing slash to /wp-admin RewriteCond %{REQUEST_URI} ^.*/wp-admin$ RewriteRule ^(.+)$ $1/ [R=301,L] RewriteRule . - [L] RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-.*) $2 [L] RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L] RewriteRule .* /blog/index.php [L] RewriteCond %{REQUEST_FILENAME} -f [OR] RewriteCond %{REQUEST_FILENAME} -d <IfModule mod_security.c> <Files async-upload.php> SecFilterEngine Off SecFilterScanPOST Off </Files> </IfModule>