I'm sorry to hear you've had a bad experience with the plugin, and I'd be very keen to help you troubleshoot any issues (especially in regards to the appearance of your default gallery). It sounds like you're experiencing a conflict with another plugin, or perhaps your theme.
The original, Basic version of Optimizer you're using has only ever supported the popular [nggallery id=x] shortcode, and thus, does not load the required scripts and styles for other NextGEN shortcodes to properly display and function. This is explained very clearly upfront before you download on the plugin's main page at the WordPress repository.
This basic functionality in fact works great for most people, and originates from code I'd developed for a client with this specific requirement in mind. I later went on to develop the Premium version for users who liked the plugin and wanted support for extra shortcodes and settings. This model enables the plugin to remain under constant development, and has resulted in many improvements so far...with support for lots of extra functions (and requested features) on the way.
Finally, I'm not sure exactly what kind of performance you're referring to, but in terms of page load speed on non-gallery pages, measured, real world testing consistently shows a marked improvement.