First of all, open source versions often are just not as good. I was a fan of gitlab for personal projects, but after trying it for a couple of months on a company's project, we moved back to github because of all the bugs and low perfomance.
When did you try GitLab, and was it self-hosted or GitLab.com? We've been working on improving performance, especially on GitLab.com, for the last two years now. Having started around then I can definitely say it was pretty miserable back then, but it's infinitely better now.
Second, who's going to pay for all the servers?