delphisvn now includes Subversion 1.4.0 client DLL. It can still use the previous (Subversion 1.3.2) client DLL.
Note: Using the Subversion 1.4.0 client library may automatically upgrade your working copy format which will make your working copy directories unusable by pre-1.4.0 clients.
For more information, see Subversion 1.4.0 Release Notes.
I've just upgraded my home computer to use Subversion 1.4.0 and TortoiseSVN 1.4.0.
The speed improvement is amazing! Kudos to the Subversion dev team!