Are you using the IE Plugin client or the Ajax Client?
I saw there was a bug in QV11 SR1 related to "slow exports to excel" that was supposedly corrected for SR2 so that might be a thing to check into (it was listed in the release notes).
From how I understand the excel exports, the IE Plugin generates the export client side while the Ajax client triggers the server to generate the xls file in a folder on the server and then push the link to the client once done.
The spreadsheet is first created on the server and then moved to the client. However, this was not designed for large amount of data and the amount of data will vary based on your environment. You can add the below to the QVS settings.ini file to tell when to change over to CVS and that might help you..The default is 65500 and you would have to add it. I would set it low so it will start off as CVS..
Access users mainly export the database to the excel sheet. For step by step process you can check the following link: http://gallery.technet.microsoft.com/Access-To-Excel-Converter-00660936
By this solution you can get step by step process steps for exporting database to excel.