Spiders/Bots problem slow down my site

You can use .htaccess file to block bots with some UserAgent. Add following lines after “RewriteEngine on” :

RewriteCond %{HTTP_USER_AGENT} Purebot [NC,OR] RewriteCond %{HTTP_USER_AGENT} DotBot [NC,OR] RewriteCond %{HTTP_USER_AGENT} Ezooms [NC,OR] RewriteCond %{HTTP_USER_AGENT} Robot [NC,OR] RewriteCond %{HTTP_USER_AGENT} ichiro [NC,OR] RewriteCond %{HTTP_USER_AGENT} VoilaBot [NC,OR] RewriteCond %{HTTP_USER_AGENT} ReGet [NC,OR] RewriteCond %{HTTP_USER_AGENT} Rankur [NC,OR] RewriteCond %{HTTP_USER_AGENT} cmsworldmap [NC,OR] RewriteCond %{HTTP_USER_AGENT} libwww-perl [NC,OR] RewriteCond %{HTTP_USER_AGENT} SurveyBot [NC,OR] RewriteCond %{HTTP_USER_AGENT} RadioClicker [NC,OR] RewriteCond %{HTTP_USER_AGENT} Embedly [NC,OR] RewriteCond %{HTTP_USER_AGENT} TweetmemeBot [NC,OR] RewriteCond %{HTTP_USER_AGENT} discobot [NC,OR] RewriteCond %{HTTP_USER_AGENT} AhrefsBot [NC,OR] RewriteCond %{HTTP_USER_AGENT} SearchBot [NC,OR] RewriteCond %{HTTP_USER_AGENT} LinkpadBot [NC,OR] RewriteCond %{HTTP_USER_AGENT} bingbot [NC,OR] RewriteCond %{HTTP_USER_AGENT} SISTRIX [NC,OR] RewriteCond %{HTTP_USER_AGENT} Flexum [NC,OR] RewriteCond %{HTTP_USER_AGENT} BLEXbot [NC,OR] RewriteCond %{HTTP_USER_AGENT} siteexplorer [NC,OR] RewriteCond %{HTTP_USER_AGENT} kmbot RewriteRule ^.* - [F,L]

I recommend changing your wordpress login page from wp-login.php to something different.

Then, in your .htaccess set your wp-login.php page to be blocked, like this:

#prevents access to wp-login
    <Files wp-login.php>
    order allow,deny
    deny from all
    </Files>

you can google to see different ways to change your login page. It is not too difficult, and will reduce the bots to almost zero.