ScriptLink does not load until after web parts

I have a master page with a SharePoint link in it.

<SharePoint:Scriptlink runat="server" Name="~siteCollection/SiteAssets/menu/js/menubar.js" Language="javascript" />

I have web parts on the page that run scripts. 
Can someone explain why the SharePoint Scriptlink does not execute until after all web parts have been loaded?

I put the script in the master to force it to load first.  Before anything else loads.