In a Mercurial repository with ~20.000 commits, it sometimes takes more than 6 seconds for file details to show up.
Looking at the duration of service requests, the main time spent is in diffusion.lastmodifiedquery (6 seconds) and a call to hg log --template '{node}' --limit 1 --removed --rev 'reverse(ancestors('\''***rev here***'\''))' -- '***path here*** (6 seconds).
This happens on multiple levels of browsing, starting at the root. The ***path here*** above frequently points to a folder with a large history.
If there is any information I can provide, please let me know.