One thing I dislike very much about the UI in general is the fixed/sticky header, which wastes precious vertical space (especially with an Ultra Wide monitor since there's mostly nothing in it). Also due to its color I find it distracting when reading code, would love I could just scroll down to make it go away.
Most of the time I'm using the left sidebar, not the top one. For the few times I want to use the top bar, scrolling up really isn't an issue. Note that GitHub also doesn't have this.
For the assignee dropdowm, it was roughly 6-8 weeks ago. I just went back to an old project and things seem to be much faster now.
In the past 3 years, I had to work on Gitlab a few times (for a few months every time), and at the end of every project, I had this feeling of: it was slow (push speed at the time could take 5-10 seconds when it was almost instant on Github), and basically all request were slow (dynamic dropdowns, posting a comment...). It is good to see you are focused on fixing these problems though :)
For the UI thing, a few points:
- imho, there's just too much on screen. I would say Gitlab is to Github what IntelliJ is to Atom: too much features I don't want to use/see. They just distract me. - the container in the middle is too large, there too many word per line and things get hard to read - Even with the breadcrumb, it is really hard to see "where" I am in the app (which project) - In the issue details page, it is hard to see the continuity of the comments, what is a comment and what is an action ("assignee changed from to..."). I cannot quickly go through an issue an getting on overview of the discussion easily.
I think these are mostly tiny UI things to change, and only with some typeography improvements, some borders and better contrasts, things will be a lot more clear.
Of course, all of this is highly subjective.
5mn of CSS tweaks: https://imgur.com/a/FLTJT (ofc it adds other issues/concerns, but you get the idea, I am no designer, but sensible to nice UIs)
Also, I am wondering if you were looking at a much older version of GitLab with the discussion and the UI being unreadable. We've made a ton of improvements to our UI in the past year. If you are looking at a recent version, can you tell me what is unreadable about the discussions and the UI in general? That way we can fix it.