https://github.com/D-Programming-Language/tools/pull/64 introduces this. Basically calls like exists("filename") and isDir("filename") make one stat call each, whereas calling stat once offers all information. The extra calls are not recorded with yap() either. Excessive stat() calls are a major scalability issue. Arguably the best fix would be to offer a nice API as noted in the pull request.
This issue has been transferred to https://github.com/dlang/tools/issues/409