In a report by WP Rocket, AddThis added an additional 1.22-1.28 seconds on a websites load time and increased the overall page size by 726.3 KB. That’s a considerable amount for a few sharing buttons that can be replicated with basic HTML, and CSS.
ShareThis which is another large contender in the social sharing buttons also added a considerable amount of time to a website’s load time adding anywhere between 1.31 seconds and 1.8 seconds on top of the websites load time but only increasing the size by 686.6 KB.
5. Async Social
While having the name Async in its name the plugin is not loading anything lazily. Async Social was shown to increase the load time of your website by 1.33 seconds to 1.57 seconds slightly slower than that of ShareThis. It also increased the page size by 1.2 MB.
4. Jetpack – Official Buttons
While these are not the optimized JetPack buttons they are included in the plugin and they were found to add an additional 1.35 seconds to 1.41 seconds to your website load time and increasing the page size by 1.2 MB.
3. Really Simple Share
The only thing this plugin does easily is increasing your load time. In testing the plugins added about 1.5 seconds to your load time and increased your page size by 1.4 MB. Making it an extremely heavy plugin.
2. Ultimate Social Media & Share: Bottom of Post
This plugin truly is simple for the fact that it deserves two spots on this list and both are for the slowest sharing button. By only enabling sharing buttons for the bottom of the psot the plugin added between 1.8 and 2 seconds to your website load time and added 1.4 MB to your page size.
1. Ultimate Social Media & Share: Bottom of Post + Sidebar Widget
This plugin again in last place was found to further increase the load time dramatically by adding 2.1 and 2.13 seconds to your load time and increased your page size by 1.8 MB. For reference the average website size according to GtMetrix is about 1.65MB in size. This plugin also has a considerable amount of http requests giving it the crown as the slowest social sharing plugin.