There are times when you are troubleshooting your Facebook ads performance, the cost for landing page view is higher than usual – I would say more thatn RM4-5 is consider high. It could be your ads or could be one of the technical issue.

Over-optimize caching plugin might lead to this.

For WP-Rocket, I strongly suggest to disabled or uncheck:

• Load Javascript deferred
• Delay Javascript execution

Some client use different plugin but the setting is almost the same. First troubleshooting step is to uncheck these two options and remember to clear cache.