Website constant error 500 when opening multiple links

Hi There,

Users have been reporting some delay in load times and error 500 being pretty common when opening multiple links at the same time.

I have enabled debugging and have attached the file below. There is a number of small issues I can fix but I am unsure about the ones in regards to plugins which are built into the site which I can not update (Or if there have been updates I have not received emails)

I have attached the log file as there doesn’t seem to be anything private in it.

Example:

[09-Nov-2016 23:46:54 UTC] PHP Notice:  Undefined variable: class in /home/imminent/public_html/wp-content/themes/gameaddict/pagebuilder/blocks/parallax-block.php on line 243
[09-Nov-2016 23:46:54 UTC] PHP Notice:  Undefined variable: termsarray in /home/imminent/public_html/wp-content/themes/gameaddict/widgets/portfoliowidget/portfoliowdg.php on line 53
[09-Nov-2016 23:46:56 UTC] PHP Notice:  bbp_setup_current_user was called <strong>incorrectly</strong>. The current user is being initialized without using $wp->init(). Please see <a href="https://codex.wordpress.org/Debugging_in_WordPress">Debugging in WordPress</a> for more information. (This message was added in version 2.3.) in /home/imminent/public_html/wp-includes/functions.php on line 3996
[10-Nov-2016 00:16:35 UTC] PHP Notice:  Undefined variable: nameError in /home/imminent/public_html/wp-content/themes/gameaddict/pagebuilder/blocks/contactform-block.php on line 238
[10-Nov-2016 00:16:35 UTC] PHP Notice:  Undefined variable: emailError in /home/imminent/public_html/wp-content/themes/gameaddict/pagebuilder/blocks/contactform-block.php on line 245
[10-Nov-2016 00:16:35 UTC] PHP Notice:  Undefined variable: commentError in /home/imminent/public_html/wp-content/themes/gameaddict/pagebuilder/blocks/contactform-block.php on line 256
[10-Nov-2016 00:16:35 UTC] PHP Notice:  Undefined variable: termsarray in /home/imminent/public_html/wp-content/themes/gameaddict/widgets/portfoliowidget/portfoliowdg.php on line 53