Continuing Performance & Memory problems - Joomla! Forum - community, help and support

i'm having performance issues several web sites on same shared hosting environment. sites use joomla 3.6.2, running on php 5.6 , on 7.0.9. issues see when logged in backend or visiting front end, include:

error 500 - internal server error. error encountered while processing request. typically temporary condition. please contact web site owner further assistance.

simply refreshing browser restores page viewing. but, takes minute's worth of refreshes.

in addition, see virtual memory maxed out @ 2048 hours on end in middle of night. cpu usage @ 50 percent on night. , cpanel reports:

your site has been limited within past 24 hours. virtual memory resources limited site. i/o usage resources limited site.

in addition, see messages in cpanel's resources usage area like:

[wed oct 12 11:26:05.451947 2016] [:error] [pid 491487:tid 140270362298112] (12)cannot allocate memory: [client 192.243.55.136:56442] couldn't create child process: /opt/suphp/sbin/suphp /home/xxxxxx/public_html/index.php

joomla system information reports memory_limit @ 512m. opened ticket @ host , put in php.ini file, referenced in htaccess, in 1 site public_html folder , set limit @ 1024m. not seem help.

anyone have ideas?

did managed problem resolved?

the errors seeing due account being throttled/limited due memory allocated account (not php memory_limit) being maxed out.

did problem started or has been way while?

did install new extensions or themes?