Tom,
your hardware looks to be on the low side but even then should not be taking close to a minute for a simple stretch.
Do you have lots of windows (ie plan, sections, details, schedules etc) open?Having many open will place a significant burden on the computer (processor cycles and RAM) as it tries to keep these background windows updated.
If not I would suggest saving the project as a solo project and re-establishing the share to purge the file and hopefully remove any anomalies