I've been running the TK Lamp appliance on VirtualBox for the past month or so and I was quite happy with it, until a few days ago when I noticed the following:
The appliance takes about 3-4 times longer to start (until the blue screen with administration details is shown).
After it has started, the first time I open the webmin console, it takes about 30-40seconds for the login page to load, but it works super fast afterwards.
If I try to log in through SSH, it takes a considerably longer time for the server to respond asking for a password than it did before.
As far as I know, I haven't done anything in the past few days that might influence this. The only thing I remember doing is cleaning out three giant log files which were 3GB each. I'm running a Windows 7 host, and the PC has 8GB of ram and a quad core Intel Sandy Bridge processor.