We ran an gitlab instance for about eight years and it worked flawlesly[1] for a team of ~20, with quite a few active repos (i.e. constantly pushing), some of them being generously large, running several pipelines on most of them.
PS: gitorious was aquired by gitlab, not gitolite. My bad.
[1]: once we pumped up _LOT_ of RAM into it that is
I cannot disclose details (we are premium customer and the bug reports would disclose my employer and identity), but every second week our Gitlab integration is blocked by some real shitty bug. Most common thing: Gitlab has a feature we need, but its only usable via WebUI and the API endpoint is broken or lacking in necessary details. So we cannot automate things that are very manpower-intensive.
Most of our devs were annoyed by some external toolings that supported Github but not Gitlab, Gitlab being slow or down, markdown rendering being terrible slow as well as almost all of the PR additions (e.g. eslint checks, test coverage reports etc) being in the top tiers (with pricings being out of scope for us).