Most efficient setup

Which would be a more efficient setup.

What we are thinking of having is either :

database1 -> table1,  table2, table3

database2 -> table1, table2, table3

database3 -> table1, table2, table3.

OR

database ->   database1table1, database1table2, database3table1   etc.

which is the better setup for load balancing, speed wise etc.

Also we need to be able to search all the tables acrosss all the databases.