mrbkr86 on "query excerpt causing MySQL"

Hello all from last few weeks my website was very slow and after few days my hosting provider have suspended my hosting. They told me that

"It was quite a bit worse this time - the queries were backed up, some for over 10 minutes, and in the end it was causing MySQL to use about 800% of the server's CPU (8 full cores) - so we had to suspend it.
"

Here is the query excerpt we have:

Copying to tmp table | SELECT DISTINCT post_title, ID, post_type, post_name
FROM wp_posts wposts
LEFT JOIN wp_postmet

This was taking 10-20 seconds to execute.

I am not a wordpress developer so i need your help guys :/