JBrowse "details" page poor performance for large genomes

[scottcain]

I'm pretty sure that the performace problems for JBrowse with the details page is associated with the time required to fetch DNA sequence, and this is bad for mouse, rat and human due to large genes. I'm guessing a plugin already exists that will fix this issue, either by more effectively deferring the fetch, or eliminating the fetching altogether.

Related to this issue: I'd like a "JBrowse" or "Genome browser" label to apply to this and any issues related to the transcript viewer.