You should add the changes one more time. The last update doesn't include that part. This will be included in the new major version of wpDiscuz (no ETA).

The steps you should do: 

https://gvectors.com/forum/wpdiscuz-comment-plugin-support/mysql-performance-wp_wc_users_voted/#post-17613

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Could you please show the indexes of wp_wc_users_voted table fields? And, please let us know what MySQL version you use? Also, please make sure this table engine is InnoDB.

I have same problem again 

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Thanks for your kind replay. 

Yes I am using separated count :) 

One question is why do you write down each vote, and just one meta filed in comments meta table, with total negative and positive values? 

are there any hooks or action which we can use to display data and on vote to update this metafields (if we try to do some own solution)

Thanks!

Currently, if you're not using the "separate count" value for the "Comment voting statistic mode" option and you've not installed the wpDiscuz Comment Author Info and wpDiscuz Comment Author Info addons, there won't be any problems if you empty  wp_wc_users_voted table. 

However, we don't recommend you to empty it. Probably in the future, you'll decide to use the separate count option or some add-ons. 

If I empty table wp_wc_users_voted will I lose a number of votes for comments or this table is just holding data to prevent user to double vote on some comments? 

I investigate on this and it holds an each vote per comment? I am right?

Thanks. 

We'll fix this issue in the next version release. You will be able to update the wpDiscuz plugin without worries.