VM very slow after snapshot recover

Question

We have here a Citrix XenCenter with few Virtualized machines. So last week we had to recover a VM from an old snapshot (the current one got lost because of a miss configuration in file permissions). The thing is the recovered snapshot is working so slow that none of the systems on it work properly (Apache tomcat with some applications).

Is there some step that should be followed in a snapshot recover before start the virtual machine?

The VM in question is running a Ubuntu:

$lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.2 LTS
Release:        14.04
Codename:       trusty

uname -mrsn
Linux xxxxx 3.16.0-30-generic x86_64

Thanks.