Thanks for posting your issue.
The total load time is all HTML, scripts and CSS are loaded into the browser. If all work well the total load time should not change. The total load time. This plugin change when your scripts load and not how fast they load.
Please see also: https://developers.google.com/speed/docs/best-practices/payload#DeferLoadingJS
The plugin can set new dependencies between some scripts and so let increase the total load theoretical, but also in that case the most important parts (the HTML DOM structure) will load faster.
Please could you describe your Shortcode Ultimate styling issues in more detail?