Firstly, the slow operation is be due to the fact that
you ran this operation from your workstation (via remote
desktop even) on a database that was located on a server
somewhere out on the LAN. Any operation that is likely to
take a long time like mass deletions and such are better
performed on the server locally.

Secondly, why pin? Why not just share and branch? You
will effectively get a copy of the project based on the
label you choose.

"When you pin a shared file, however, you cannot
thereafter make changes to it. Pinning is not the same as
branching; for one thing, you are not making a copy of
the file. For another, you are not planning to change the
file. You are sticking a pin into the file so that a
particular version of the file becomes the version that
is part of your project."

I dunno - maybe thats what you wanted to do...