We have now released version 2 of EPiServer.ServiceLocation.StructureMap. This version has a dependency against version 4.5.2 of the unsigned version of StructureMap. According to release notes in StructureMap documentation the newer version contains (among other things) performance improvments.
There are some nuget issues that could be good to know about when updating EPiServer.ServiceLocation.StructureMap. Nuget will not remove references to the packages structuremap-signed and structuremap.web-signed used by version 1 of EPiServer.ServiceLocation.StructureMap during update. So a recommendation after updating is to uninstall those packages. Also any existing binding redirects to the signed version of StructureMap assembly will remain in web.config.
An alternative to update package is to first uninstall package EPiServer.ServiceLocation.StructureMap, make sure to select option "Remove dependencies". If you have an dependency to package EPiServer.CMS you must also select option "Force uninstall". Then install version 2 of package EPiServer.ServiceLocation.StructureMap. Even in this case there might be old binding redirects left in web.config.
The package has been tested with CMS and we are currently testing it with other products such as Commerce and Find, to make sure it is compatible with other products as well.