More table or more database for better performance? Lets say 1 website need 10 database table to work and i want a database pool that 40.000+ website will be inside.

Which option is better for server performance?

1) 400 databases each have 1000 table?

2) 4000 databases each have 100 table?

Update: I see i need to put some more details, sorry for trying to ask simple as much as i can.
Site will based on wordpress multisite with http://wordpress.org/extend/plugins/hyperdb/

1 website with 10 database table generally wont pass 6-7 mb as total database info. There will be 9-10 heavy website that will have serious database info, i will put them in a special database. ( lets say 4096 database, 96 reserve for vip,heavy sites and split all other sites in 4000 database )

Server is:
http://www.wiredtree.com/managedhybrid/
After reaching some point, i am planning move to pure dedicated server which will based on raid10 15k RPM SAS mysql discs and different media discs

So 40.000 sites but all of them sharing same php files, just different databases and different upload folders. This is how wordpress.com working. Same rules but my sites wont be a blog.

Please ask what other info do you want, i will try to explain more. I am very sorry if i break any rules or something. 

( Sorry for bad english too :P )
Performance shouldn't be a concern: security, consistency, data integrity should be


Security: If each web site has a database this implies that the data for that web site is 
private and separate. So 40000 databases with 10 tables each.
Consistency: managing 40k websites requires utter consistency. Why pick 400x1000 or 4000x100? How will you separate tables? How do you know which site uses which set of tables in which DB?
Data integrity: If you restore one database, do you really want to reset the data for another 399 or 3999 websites too?


So: 40k databases, one per web site.

Finally, do you have 40k web sites or is this premature optimisation?