That's definitely fair, and warrented. We haven't really had the resources for (relatively) long to put into performance when we were still in early stages. However we've constantly been improving that, to the point where I truly doubt you'd find that we suffer disproportionately from performance issues more than any competitor.
Before I worked here, I was on a team that evaluated different devops tools, and I felt the same apprehension about the uptime. But we eventually chose gitlab, and the only real downtime we experienced was during the 2017 outage. And we liked having the option to switch to self-hosted if it became too much of an issue