While you are converting physical environment to virtual environment, you will meet the problem that it takes long time. Here's practise how to increase performance.

• Step 1 : Open converter-worker.xml configuration file. It's located in "%ALLUSERSPROFILE%\VMware\VMware vCenter Converter Standalone"
• Step 2 : Set key config/nfc/useSsl to false. Then save configuration file
• Step 3 : Restart "VMware vCenter Converter Standalone Worker" Service

    ...  
    <nfc>  
       <readTimeoutMs>120000</readTimeoutMs>  
       <useSsl>false</useSsl>  
    ...