@SNCR_1; birde bu şekilde deneyebilir misiniz?

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^tag/(.*)$ index.php?do=search&subaction=search&s=$1 [NC,L]
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

</IfModule>

<IfModule mod_deflate.c>
AddOutputFilterByType DEFLATE text/html text/xml text/css text/plain
AddOutputFilterByType DEFLATE image/svg+xml application/xhtml+xml application/xml
AddOutputFilterByType DEFLATE application/rdf+xml application/rss+xml application/atom+xml
AddOutputFilterByType DEFLATE text/javascript application/javascript application/x-javascript
AddOutputFilterByType DEFLATE application/x-font-ttf application/x-font-otf
AddOutputFilterByType DEFLATE font/truetype font/opentype
</IfModule>