Calculate sum and count only for widgets using them

Module is running _votingapi_select recursively when building vote up/down widget.

When loading node with lots of comments, displaying 300 comments per page, I get vote up/down calling _votingapi_select 1806 times.

This happens in vud_widget_proxy() in vud.theme.inc.
votingapi_select_single_result_value being() called 4 times + one votingapi_select_single_vote_value(). Module selects: (1) user_vote, (2) sum, (3) count, (4) positives and (5) negatives (in my widget I actually use only sum).
Plus one more votingapi_select_single_result_value() call more in vud_votes_proxy() (again for sum).
In total that will be 6 queries.

votingapi_select_single_result_value makes a SQL query each time it is called so that's will be 6 times x 300 comments = 1800 queries + 6 queries from node widget calls = 1806 SQL queries!
Consider, that when displaying 50 comments per page Vote Up/Down makes 306 extra queries. This is really dramatic.

This must be optimized or some caching mechanism needs to be added to be used with memcache.