64 bit virtualbox performance?
 

Hopefully not a dumb question but I finally got with the times and have some 64bit hardware now and tried to run virtualbox and the performance was pretty bad, is there that much more overhead?

So long story, basically I use laptops for everything since I have two kids who want/need systems I buy a used laptop and use it for a couple years and pass it down to them. each kid has a Dell Latitude D620 and I bought a Latitude D630 for my 'server'. The 620's had a couple different cpu choices and neither of mine were 64 bit capable so I found that the 630 was the first model where all the cpu choices were 64 bit so I found one of those with a couple broken ports last summer for $100. I upgraded to Slackware 14.0 x64 at that time then got busy with $big_work_project$ and never got back to it until now. I installed the latest virtualbox and started setting up a simple Slackware 14.1 guest like always and running it maxed both cpu cores and all memory on the host. Previously with one of the D620's running Slackware 14 as the host I could run at least three guests before running into performance issues if I tried a 4th. Unfortunately I've changed too many variables, is it simply changing to Slackware x64, is it the latest virtualbox, is it multilib? Should I be able to run 1,2, or 3 small guests like before?

do you have cpu virtualisation on your cpu ?
is it turned on ? (settings-system-acceleration)

If the host OS has only 2 G of RAM, IMO, that's enough "to boot" and not suitable for 3 or 4 VMs to run simultaneously.
I had 8 G of RAM on my desktop and assigning 4096 or 5120 to VMs and running 2 was "ok".
Now I have 16 G of RAM and running 4 VMs is easy.

My previous 32 bit host only has 2G of RAM also. A few years ago at work we built a new Citrix farm and they sent everyone to training. I built a W2k3 domain controller, another w2k3 box for Metaframe 5 and another W2k3 box for a web front end. I had all three running and could use the Linux Citrix client and connect to my citrix 'Farm'.
Thats why I'm wondering is the 64bit overhead that much that even on a little newer hardware I can't do the same?