SymptomsVirtual machine performance is slow either from the start up or while using a certain application.
CauseThere could be several reasons to the slowness.
1. Using the old (not the latest) build of Parallels Desktop application
2. Lack of resources assigned to the virtual machine
3. Multiple Anti-virus programs or virus
4. Presence of unused files in virtual machine
5. Too many or conflicting start up items
6. Too many virtual machines running
ResolutionIn case you encounter one of these error messages while launching the Virtual Machine
Your virtual machine may run slow because virtualization support is disabled on your Mac.
The virtual machine performance may be degraded because the hardware virtualization support is disabled on the host computer.
Follow the Knowledge base article 10123
If Windows is slow at the Startup only:
1. Start Windows OS and click "Start" => "Run" and type "msconfig", click OK.
2. Go to "Startup" tab => un-check the unwanted application in this window => click "Apply" and "OK"
3. Go to "Services" tab and enable the option "Hide all Microsoft services" and disable all the unwanted non-microsoft services
4. Click on "Apply" and "OK".
5. Restart Windows to check the improvement in performance.
General Performance troubleshooting
1. Download and Install the latest build for your version of Parallels Desktop from the below locations:
Parallels Desktop 8
Parallels Desktop 7
Parallels Desktop 6
2. Start Parallels Desktop application but do not start the Virtual Machine
> Go to Configure => go to General tab => assign the RAM by dragging the slider within the recommended range, set CPUs number to 1.
> Switch to "Options" tab => go to "Optimization " => "Enable Faster Virtual Machine" in the drop down list
> Enable "Adaptive Hypervisor" => enable "Tune Windows for Speed"
> Go to "Sharing" => Disable "Smart Mount"
> Go to Hardware => "Boot Order" => make sure that "Hard disk 1" is the first boot device from the top by re-order the devices using the arrow keys on the right hand side of the pane.
> Close the Configure window.
3. Start Windows Operating System and click "Start" => "Run" and hit "Enter/Return'=>type "%temp%" and hit Enter/Return key on your keyboard=> select all files under this folder and delete them permanently (Empty Recycle Bin).
4. Click "Start" => "Run" and hit "Enter/Return'=>type "temp" and hit Enter/Return key on your keyboard=> select all files under this folder and delete them permanently (Empty Recycle Bin).
5. Click "Start" => "Run" and hit "Enter/Return'=>type "recent"and hit Enter/Return key on your keyboard => select all files under this recent folder and delete them permanently (Empty Recycle Bin).
6. Click "Start" => "Control Panel" => "Add/Remove Programs" in Windows XP or "Programs and Feature/ Uninstall Programs" in Windows 7 and uninstall unwanted or unused applications.
7. Free up some space in C: drive by deleting unwanted files or moving files from C: drive to other drive.
8. Try not to run several virtual machines at the same time, because each virtual machine consumes a considerable amount of resources and can slow down overall Mac OS performance.
9. Make sure Time Machine backup is not being performed at the moment. The backup creation process while running may slow down overall system performance.
10. Use Windows Task Manager to troubleshoot the performance issues. Go to Devices menu in Parallels Desktop menu --> Keyboard --> Ctrl+Alt+Del and follow instructions in this KB article: How to use and troubleshoot issues with Windows Task Manager.
If the performance does not improve follow the instructions below to run Defragmentation on the system.
Windows XP: Click on "Start" => "All Programs" => "Accessories" => "System Tools" => Defragment. For more info please read the Microsoft KB article.
Windows 7: Click "Start/Pearl" => in the search box type defragment and select the first program listed. For more info please read the Microsoft KB article.
Start defragmenting the hard drive.
Try removing Antivirus from Windows Operating System:
1.Start Windows OS and click “Start” => “Control Panel” => “Add/Remove Programs” in Windows XP or “Programs and Features” in Windows 7.
2. Locate the Antivirus installed on the system from the list and click on “Uninstall/Remove”.