My server response became really bad. Odoo websites need 11+ seconds to load. This all started happening when the server was overloaded and odoo started crashing. After that I added CPUs and RAM. 

Now the server works, the rpc2xml calls work like 300% faster then before, but the loading in browser became 3-4 times slower.

The server has 30 odoo databases. The server has 4 cores and 8GB ram and 4BG swap. Before when the pages loaded quicker it had 26 odoo datavases, 2 cores and 4GB of ram.

I added to the odoo config:

max_cron_threads = 2
workers = 8
limit_time_cpu = 600
limit_time_real = 1200
limit_request = 8192
limit_memory_soft = 5368709120
limit_memory_hard = 6442450944

and changed postgresql config to the values gotten from PG tune. 

What can I do or what could be the cause for the bad loading times?