Slow startup on all secondary computers

I am running Windows 7 32-bit on all 3 of the computers I'm testing on- two desktops of roughly equal performance, and a netbook.

I set up all of the PortableApps things on my desktop computer, and it is in a Dropbox folder synced to the rest of my computers. Startup time for the PortableApps.com launcher is very fast on this computer- a couple of seconds, no issues whatsoever. I don't have more than, say, 20, apps installed.

However, on my other desktop, and on my netbook, the launcher takes a very, very long time to load initially. The hard drive performance isn't likely to be the issue here, nor are viruses or background processes.

Are there any reasons anyone can offer to explain why PortableApps.com's launcher is being so slow on near-identical systems?