Can you enable debug mode and send us debug info populated below page. It will show how much memory used and which query uses more memory.
DEBUG MODE can be enabled by navigating to “Tools” -> “Maintenance” page under “Debug mode” title there is “Enable debug mode” button. After enabling debug mode you logged in as admin will see queries to database, time for each query, and memory usage information at the bottom of each page.
Then visit your homepage and send us all debug info via contact us form. We will see hat can be done.