Debug errors: advanced-cache.php

I am trying to figure out why my wp site has become so slow recently. I turned on debugging and received the following errors:

Notice: Undefined index: qcABC in /home/content/14/9074414/html/wp-content/advanced-cache.php on line 50

Warning: Cannot modify header information - headers already sent by (output started at /home/content/14/9074414/html/wp-content/advanced-cache.php:50) in /home/content/14/9074414/html/wp-content/advanced-cache.php on line 52

Warning: Cannot modify header information - headers already sent by (output started at /home/content/14/9074414/html/wp-content/advanced-cache.php:50) in /home/content/14/9074414/html/wp-content/advanced-cache.php on line 53

Warning: Cannot modify header information - headers already sent by (output started at /home/content/14/9074414/html/wp-content/advanced-cache.php:50) in /home/content/14/9074414/html/wp-content/advanced-cache.php on line 54

Warning: Cannot modify header information - headers already sent by (output started at /home/content/14/9074414/html/wp-content/advanced-cache.php:50) in /home/content/14/9074414/html/wp-content/advanced-cache.php on line 55

Might these errors be affecting my site? Should I be concerned?

Thanks.

Diyg