I've experienced this issue first-hand, where the free VMware vCenter Converter Standalone 5.0 is much slower than earlier Converter releases, during the cloning of physical to virtual disk phase.
I canceled the slow job pictured below* and performed the recommended fix, restarted the already configured conversion job, and immediately saw dramatically reduced estimated times to completion, about 3x faster for my particular situation.
The fix involves editing one xml file on the physical machine being converted, to avoid SSL related slowdown, takes about a minute to do, well worth it for the many hours of conversion time it saves. Here's the fix!
*Just a reminder, this is the free version of VMware Converter that you can install on a running Windows based machine (Windows XP/7, Windows 2003/2008, etc), no reboot required. You then step through the simple wizard, and convert that same physical machine into an ESX/ESXi hosted virtual machine (P2V), automagically. Works very well for a vast majority of systems. Admittedly, dynamic volumes or drive extender can be problematic, the screenshot below was sped-up, but later failed at roughly 47%, due to drive extender related issues. That's OK, converter never claimed to handle those situations anyway, was just giving it a shot, and grabbing some screenshots. I'm working on alternative methods for tricker physical machines (sector-by-sector copy and/or RDM mappings, etc.)...stay tuned!
Dec 26 2011 Update: Yes, I can handle migrating Windows Home Server with its Drive Extender, using a combination of RDM mappings and VMware Converter: TinkerTry.com/rdm4sata
Mar. 05, 2013 Update: New article spotted, with a potentially helpful scripted way for you to handle disabling SSL, check it out: Automatically Disable SSL – VMware Converter, Posted by Brian Graf, on February 27, 2013, here's an excerpt:
After doing WAY too many conversions with converter I decided I was sick and tired of turning off the SSL encryption manually, closing the open files and folders, and restarting the VMware converter worker service.