The Skype and Chrome changes had a minimal impact.
I followed one of the suggestions in the following makeuseof article, and it dropped my disk usage from 100% to 3 or 4% immediately - I stopped the windows search service and I disabled it.
http://www.makeuseof.com/tag/4-tips-fix-100-disk-usage-improve-windows-performance/
To stop this, and prevent it from happening during your current session (until Windows is rebooted) open the Command Prompt (the quickest way is by right-clicking the Start button and selecting Command Prompt (Admin)) and enter the following:
net.exe stop “Windows search”
To permanently disable Windows Search or Indexing, press Windows
- R, enterservices.exe, and hit Enter. In the Services window that opens find the Windows Search entry and double-click it to open the Windows Search Propertieswindow. Under Startup type, select Disabled. Here you can click Stop to abort the service. Click OK to save your changes.