There is no ThinApp package.ini parameter called Download=0.. Streaming or local deployment is in a Horizon Workspace implementation purely a Horizon Agent setting.
I would like you to first disable Horizon management on your package. This way we can see if the poor performance is related to your package or the fact it is Horizon enabled.
If you don't know how to disable Horizon Workspace manageability here's how to do it:
1. Open your package's project folder
2. Open package.ini
3. Disable these parameters by adding a semicolon in front of them:
;AppID=GenID
;NotificationDLLs=HorizonPlugin.dll
4. Rebuild your project folder.