If SCMHead.HeadByItem.findHead(Item) is a hot code path then there are some caching optimizations I could apply, but a brief code inspection suggests that it should not be the hot path for you.

stephenconnolly Classic uses `SCMHeadCategory` and renders it relatively quickly compared to blueocean. See https://ci.jenkins.io/job/Core/job/jenkins/view/change-requests/ vs https://ci.jenkins.io/blue/organizations/jenkins/Core%2Fjenkins/pr. That prompted us to think this might help us. I tried to run profiler but could not get consistent hot spot as creating PR based data set is not easy.

In one of the profiler test this line came up, https://github.com/jenkinsci/blueocean-plugin/blob/4f595b217795096240fff6c4bbd8af1921282b18/blueocean-pipeline-api-impl/src/main/java/io/jenkins/blueocean/rest/impl/pipeline/BranchImpl.java#L54. But again it was based on the data set I was using which was not big enough to trigger proper hot spot.

Confirmed that this is still an issue

vivek stephenconnolly did I see correctly that in the new branch source that we've got a more efficient way of searching for branches that are PRs?

can anyone confirm if this is helped by 1.2/newer releases of late? I tried with link above and it seemed "ok" but there are many other variables in my link speed. 

I ran into this recently and the issue was actually failing connections to Sonarqube. Any plugins you have installed may be calling APIs for the PR builds when you load the PR tab. If those calls stall or get connection timeouts, they will block the loading of the page view. This is surely a bug since the page view should not be blocked like this, but can be resolved if you resolve the underlying problems connecting to e.g. Sonarqube.