WordPress acting slowly.

My WordPress multisite has become very slow. After looking at stats etc, I installed new relic and it showed that my wp_options are responding very slow. I also see wp_domain_mapping is slow.

https://cdn.livechat-static.com/api/file/v2/lc/att-old/8801096/333eb7c8973269217c7ca050dd304b62/Screen%20Shot%202018-09-24%20at%201.33.02%20AM.png
https://cdn.livechat-static.com/api/file/v2/lc/att-old/8801096/79b28286b06d338cc2b4979c16c519c8/Screen%20Shot%202018-09-24%20at%202.13.28%20AM.png

And although I have over 700 sites under the same multisite, few sites it is showing gzip and cache is not working but others it is OK. Please help.