Custom field search plugin

Hello my name is Tiago

I am using wordpress to build a CRM (Customer Relationship Management) and i use custom field search to query the atributes of the contacts.

The contacts are simple post and their atributes are custom fields, so each contact has got about 32 custom field.
Because of this, my postmeta table has grown up a bit (has got about 30 million regists) and because of that my search is very very long.

I’ve tried to optimize the query that the plugin does to the database bu adding indexes to meta_key and meta_value, but still the time of the query is very very long.

Is there anything i can do to make this better?

Thanks a lot for the attention