Opened a case with Salesforce, but thought this issue could use some exploration.
Recently, in two of our sandboxes (one dev pro, other is full, one CS9, the other CS11), deployments via the force.com migration tool, the developer console and mavensmate deployments are taking inordinate amounts of time (15 minutes at times that the deployment remains "pending"), even for deployments of a single class/page or through the developer console. This has been persistent for a week now, and the symptoms appeared in the full sandbox after a deployment of components from the dev sandbox.
What could possibly cause this? I'm guessing it's something that Salesforce is having difficulty compiling, but I'm not aware of any way to measure the performance of component compilation.