Yes, with a little bit of work you can achieve performance scores of 100% in tools like Pingdom Tools, GT-Metrix or Pagespeed. The result to the left is actually this site, feel free to verify the test here.
Of course it all starts with ultrafast hosting (I recommend Siteground), but there are many actions you can take, from simply switching on the options in Joomla to advanced tweaking of your server and .htaccess files, but there are also very nice extensions that can greatly enhance performance, making your site ultrafast.
Joomlaseo.com is fully built and written by Simon Kloostra, SEO Specialist and Webdesigner from the Netherlands. I have also published the Joomla 3 SEO & Performance SEO book. Next to that I also sometimes blog for companies like OStraining, TemplateMonster, SEMrush and others. On the monthly Joomla Community Magazine I have also published a few articles.