No, there are no disadvantages. Caching plugins help your website to run and load faster. It is useful for providing your users with excellent user experience. This will also help you to get your website a better ranking. No harms!

Using multiple caching plugins at once may really hurt your website performance.

Each caching level will add some loads on your website hosting on the cache generation phasis.

Caching same things multiple times will only increate cache generation loads, it doesn't improve your website performance.Worse, it may increase the cache load time.

I encourage you to choose the more efficient caching system for you and stick with it.

However, you can use multiple caching plugins if they doesn't cache same things. For example, you can use Redis caching for object caching and WP Super Cache for full-page caching.

According to your post, only plugins which may enter in conflict are WP Fastest Cache and WP-Optimize. But you can disable page caching on WP-Optimize as WP Fastest Cache is also a page caching plugin.

And according to all my tests, WP Fastest Cache is better than WP Optimize on page caching.

I strongly recommend the free Cloud Flare account and a simple WP plugin like WP-Optimize (vs. Fastest Cache AND WP-Optimize). This has worked the best for me.

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When loading plugins you have an overhead to execute the plugin, and return whatever cached data it returns. If you're doing it 4 times, I'd say that that would have an impact.


It's quite a common scneario, often brought about by a slow theme.
Faster theme, better performance.


A big factor in speeding up a site is often the images. I don't recall if smush does it, but converting to webp had one of the bigger impacts on my sites.


Also, pagespeed insights weights the results over the first load, which would be when the cache is not primed, and therefore your results may well be slower. Subsequent accesses would although be quicker, which aren't tested.


I found another good way to get good speed is with a vps, and converting from apache to nginx, then putting in a caching option on the web server.


Another thing if you want to speed things up is to get a server with a faster disk, like SSDs. Not sure if you have that already?


Cheers,


Martin.