Re: How to evaluate server speed?
Use the port of a pretty cool wp server diagnostics plugin. https://bbpress.org/forums/topic/front-page-takes-50-mysql-queries?replies=15#post-9140
define( 'SAVEQUERIES', true ); to your config.php and activate this. Then go to View > Page Source and scroll to the bottom to see the diagnostics. (You can ignore all the stuff about queries. Just check out query time, page time, page render time. This tells you about the server bottlenecks.)
I just checked the numbers on my server, and I had 3.399 once and about twenty minutes later I had 0.436. This sort of thing can vary a lot, especially on shared hosting.