If I am not using many of the K2 Item View parameters (such as: gallery, introtext, user description, video, media caption, attachments, hits, etc.) would it improve my performance if I remove the code for each parameter in my K2 Template Override file.

Taking in mind that it will take sometime to setup plus it will take even more time to place content back I would not recommend that. There will no visible impact.

It is better to minify your css, js and cache all your static files.