Hi, we also had this issue. It was affecting x64 Windows 7 machines with 2GB RAM as you say. Declining unneeded superseded/expired updates on our WSUS server reduced this problem dramatically.
Have a look on this post: https://social.technet.microsoft.com/Forums/windows/en-US/4a782e40-bbd8-40b7-869d-68e3dfd1a5b4/windows-update-scan-high-memory-usage?forum=w7itproperf&prof=required
And the solution for us: Support Tip: ConfigMgr 2012 update scan fails and causes incorrect compliance status - The Official Configuration Manager Support Team Blog - Site Home - TechNet Blogs
I believe the hotfix released also resolves the issue!
Brent