I host with WPEngine.com and they ran some speed tests, results of which are as follows:
We noticed that PHP execution time is taking 18.60 seconds, and is causing drag on your page load.
Here's a breakdown to help you identify and resolve the root cause of the issue:
PHP Core code took 6.67 seconds to execute
The 'coursepress-theme' theme took 0.01 seconds to execute
25 plugins took 11.91 seconds to execute. The three slowest plugins:
'coursepress' took 4.741 seconds to execute
'marketpress' took 2.972 seconds to execute
'bb-plugin' took 1.005 seconds to execute
They asked me to ask the plugin developer (WPMU) what was the best way to significantly speed up the coursepress+marketpress plugin?