VirtualBox became slow without any noticeable reason

[ni4ni]

Hello all

I ave a very strange problem:
I installed Virtualbox on my computer about a year ago. I created several VM's during this period and everything was working fine. Each time Virtualbox said there was a newer version, I upgraded to that newer version and now I am on 4.3.12 r93733.

Then I left VBox for about 3 months. I did other things and my computer seems to be healthy in general (no noticeable slowness, malware and adware scans find nothing).
When I cam back to VBox and tried to run the same VM's I created months ago, they became very very slow. For example, Linux guest that used to start up in 3-4 minutes now takes over 10 minutes to start, each command (especially GUI ones) takes very long to accomplish. Services like Oracle RAC or Cloudera cluster takes forever to start. And it seems like the HDD is the bottleneck since it's always busy in VBox's little icon in the lower right of the screen.

Does anyone know what might be the problem ? Can it be just disk fragmentation ? Does VBox generate any garbage files that make it slower (and can be discarded) ?

Thank you

Guy

[mpack]

There is always a reason, though whether the reason is noticeable... is a subjective test.

Look at the guest task info. See who is hogging CPU or I/O bandwidth.

No, it will not be disk fragmentation. Usual suspects are anti-malware malware, or some kind of network change leading to lots of network failures.