I've used Gitlab for personal projects on a small homelab server. I ran the VM with about 1GB of Memory and 1 vCPU (a Core i3 if I recall correctly).

Loading a page could load almost instantly but most of the time it did load after 2 or 3 seconds.

Gitlab does not work well when resources are scarce, it does require a bit of a beefy server to get fast and reactive, atleast in my experience.

I've found Gitea/Gogs to be a product more focused on running something like Gitlab with much less resources.