I have an issue with Xfce and the time it takes to spawn the programs that were executing in my saved session.

Whenever I start Xfce, the window manager will proceed to restore my saved session, but this can take 10 seconds, sometimes 15 or more. This would have been fine if I had a slow computer, and these were demanding programs to start, but they are not, and the computer is fast.

The programs in question are a series of rxvt terminals, 7 of them, and my computer is a 4.12 GHz Core i7, 6 GiB of RAM and a Crucial CT64M225 SSD. During this latency period, there is no activity whatsoever that I can observe, the CPU usage is flat, i.e. 0% from my CPU graph module, there is no memory use fluctuations that I can see, there is no HDD activity.
It seems that the system is simply waiting for some task to complete, but I don't know what.

How can I eliminate this issue? Is this a problem that anyone else have?

I have this issue on two physical computers, one of them is a laptop, the other is a desktop, both have fast SSDs and are in general fast computers.

I use Slackware 13.1.0 on both computers, I use custom highly optimized kernels, but have the same issue with the standard kernel.